Come on baby light my fire

Yves Klein was a painter, sculptor, performer and self-mythologist. He was a Knight of the Order of St Sebastian, a Rosicrucian, a devotee of St Rita and a 4th-dan judo black-belt. He was Yves le Monochrome, Utopian visionary, entrepreneur of the void and sole inventor of International Klein Blue (IKB) - a deep, throbbing, adulterated ultramarine. He had schemes for an architecture carved out of jets of hot air and public sculptures made of fire. He even made the Parisian art-world's urine run b lue, after serving dyed blue cocktails at one of his riotous opening parties.

The largest exhibition ever devoted to Klein's work in Britain opens today at the Hayward Gallery, en route between Germany and Madrid; it is a show of purity and vulgarity, of fabulous calm and numbing pretension - Klein makes your eyes rock and your mind swim. Someone once said that he displayed the taste of the kind of person who'd keep an ocelot for a pet. Happily embracing bad taste, kitsch and corniness, he saw no contradiction between satori and showmanship.

Klein is best known for his blue monochrome paintings, and for his anthropometries, works in which naked female models rubbed and rolled their pigment-covered bodies over the surfaces of his paintings while the artist stood back, immaculate in his tuxedo, smoking an insouciant cigarette and shouting instructions. These astonishing human imprints, smeared, dragged and unfolding across his paintings, are a record of the spectacularly silly and - to current eyes - unconscionable performances during which they were made, yet as paintings they stare back as a kind of affirmation of bodily presence and vulnerability, whatever one thinks of them from the standpoint of sexual politics.

Born in France in 1928, Klein led a privileged, desultory and much-indulged youth. He was largely self-taught, even though both his parents were moderately successful artists. When he wasn't staring at the sky (he wanted to ban birds and clouds for spoiling the view), he gravitated towards the study of mystic Rosicrucianism and judo. He travelled, working for a picture framer in London during the late 1940s, learned to ride horses in Ireland and set out for Japan where he became one of the first foreigners to achieve the 4th dan in Kodokan judo. He taught judo in Madrid on his return to Europe, and set up a soon-to-fail Kodokan school in Paris, financed, like much else he did, by an aunt. In 1954 he published a book on Judo, and continued to teach at ahigh level until 1960.

Klein alternated between periods of self-doubt - proclaiming that he had neither a gift nor a facility for anything - and self-aggrandisement. Early in 1955 he sat in a bar and decided he was a genius. Up to this point his artistic production had remained largely in his own head, although he had produced a small catalogue of purely imaginary paintings, a book of printed, flat blocks of colour, each dated and titled after the cities he had visited. Even the catalogue's introductory text was a kind of conceptual spoof, consisting of ruled parallel lines where the words should be. But in his mind he conceived plotless, characterless novels; he had ideas for the theatre and for musical composition, and a firm view of the future of art, and of the spiritualdevelopment of mankind - a somewhat embarrassing rag-bag of Rosicrucian thought, mystical religiosity and ideas lifted from the philosopher Gaston Bachelard - in which his work was to play a crucial part.

Klein didn't so much develop as a painter as arrive, fully formed, in 1955, and he soon won the support of Pierre Restany, critic and De Gaulle aparatchik, and of the dealer Iris Clert. Within a year, during which time he experimented with painting mediaand ran the gamut of colour variations, surface inflections, materials and formats, he settled for a kind of one-colour painting in which dry IKB pigment was rollered or sponged on to the surface in such a way that it lost none of its intensity and particularity as it dried. There were to be no gestures, no handwriting, and no forms, just pure tablets of uninflected, impersonal colour - the wine-dark, Homeric blue of the ocean, the sky, and of infinite interstellar nothingness.

Klein was neither the first nor the last painter of monochromes, but he was undoubtedly the most theatrical. Nor was he to become the first artist to use the human body as a kind of living brush - that accolade must go to the anonymous paleolithic painter who pressed an earth-smeared palm on to the cave wall. His work still looks like no one else's.

The monochrome for Klein became a field of reverie, a numinous, bounded reservoir of energy. But painting alone was never enough, even though he returned to it again and again until his death. His quixotic, romantic sensibility, not to say his self-aggrandisement, led him to write to President Eisenhower in 1958 asking the UN's authority to hold a revolution in France, so that Klein could turn the country itself into his next work. He wanted atom bombs to rain IKB instead of fallout and, if there is a Red Sea and a Black Sea - why can't Klein have a Blue Sea all of his own?

He had to content himself instead with raked floors of blue pigment, rods of solid blue rain, a rotating blue disc (distantly echoing Marcel Duchamp's bicycle wheel, which Duchamp said he only made because he liked to watch it go round), a mural for a German theatre lobby and a school-room globe of the world, painted blue. Klein produced mutating bestiaries of blue organic forms, derived from the paint-saturated natural sponges he was using instead of brushes and reliefs, in which the sponges seem to sprout like strange flowers. One of the high points of the Hayward's exhilarating show is a kind of garden of these small sculptures, which seem to twist and unfold against the stark white walls with a peculiar, disembodied, luminous presence.

He went on to display the empty white gallery as a work in itself (a kind of void incarnate), to suggest some alarming theatrical performances, and to extend his colour range to include rose and gold leaf. He painted with fire, wielding a blow-torch while a friend dressed as a fireman stood attendance. "Fire," said Klein, "burns in the heart of the void as well as in the heart of man."

Yves Klein died of a heart attack at the age of 35 in 1962. He had recently returned from America, where his reception had been less than rapturous. Sidra Stich, curator of the show and author of its excellent catalogue, suggests that New York jealousiesmay have been the reason. Maybe they just didn't understand him. Klein, for all his spiritual aspirations, was a stylish and flagrant self-promoter; he was both deadly serious and a bit of a fraud. And, like all who embrace Utopian ideals, he was an heir to melancholy. When he leapt from an upstairs window into the infinite, his photo-opportunity attempt at levitation caught him suspended for ever, between the pavement and the void.

Hayward Gallery, London (0171-928 3144) until 23 April