Andy Warhol vs Banksy? This show, the first ever pairing of the two, hardly seems a fair fight. True, there are similarities between the artists - and Banksy, the anonymous and infamous graffiti artist, chooses, cheekily, to make a great deal of them.

Both engage with popular culture, aim at the iconic and use methods of mass reproduction as their primary expressive tool. Banksy plays up the link in his Marilyn Monroe-esque portrait of Kate Moss, and is helped along more generally by Warhol's inability to reply.

Both names conjure a wealth of associations, but ones that take us to radically-different places. Warhol summons imagined glimpses of star-studded, drug-fuelled parties in the silverwrapped Factory, of the blank, voyeuristic artist observing events with a twist of sardonic sadism. He brings to the mind's eye his iconic, repeated images of Marilyn and Mao.

In pictures: Warhol vs Banksy

Banksy's name goes somewhere altogether less romantic, to grimy London walls beside busy junctions where he plied his mildly criminal trade, satirising the powers that be with funny, punchy images.

Such a practice sits within a wider subculture of hoodies, free parties and a degree - even if largely imagined - of resistance to the "system".

But Warhol and Banksy's true kinship comes from their strange, ironic relationships with the market.

Both began their careers as outsiders to the commercial art world - Warhol as a magazine illustrator, Banksy rather more literally - only to become part of mainstream culture, commanding the kind of money that success-entails. Yet both artists' work remains critical of the grubby world of financial transactions.

With Banksy the antipathy is simple satire, most notable in Moron, a crude stencilled work recording the moment in an auction room when Van Gogh's sunflowers were sold for millions. Where the flowers should be Banksy has written "I can't believe you morons buy this shit." And one gets the feeling he might be speaking directly to his own market.

But Warhol's work goes far beyond satire. His critique went deep, and to somewhere bleak and empty: a mental space hinted at by his series of repeated images that fade to blankness as the ink runs out. Warhol's ambivalent exploration of a modern world full of shiny surfaces - from TV screens, to glossy magazine pages and sparkling packaging - is articulated in a subtle self-portrait he made for himself, not for sale.

In it, very simply, two headshots are overlaid, one looking at the viewer, one twisted mournfully to one side, as if acknowledging that unity in this world is impossible.

• Until 1 September. for more information, call 020 7170 9100.

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