There's a lot of cash at stake in 'The Great Swindle', Santiago Montoya's exhibition at London's Halcyon Gallery. And not simply because the Colombian artist's vast canvases - portraying the revolutionaries who stare out somberly from banknotes and the sublime landscapes printed on the flipside - are likely to resonate with collectors.

Money is the canvas in most of his works, impressed with machine-like repetition onto blocks of stainless steel or looped through slots in the metal like wads stuffed dubiously into a suitcase.

To amass it all, Montoya traded with currency collectors the world over, even travelling to India to secure cases of rupees, renminbi and old North Korean won, some discontinued, some still in play.

As a result, says Montoya, 'the money has been built into the value of the art'.

The banknote-canvases put into sardonic perspective the tenuous relationships between superpowers like Britain, China and Venezuela. In 'Money Talks', for instance, Montoya arranges the American and Chinese currencies in spellbinding contrast so from a distance they appear to spell out 'blah'.

'So Be It', a play on the word 'Soviet', is a grid of rubles featuring the churches in Red Square - powerful Soviet icons despite their disdain for religion.

Montoya's fascination with the zero plays a role in arresting neons where the digit forms the centre of a Greek zephyrus, that flowering pattern of zeros commonly seen on banknotes. Or he'll laser-cut zeros out of painterly notes and suspend them in blocks of glass. 'There's a certain grandeur in the zero,' he says by way of explanation. 'This eternal recurrence becomes so mesmerising you forget it signifies nothing.'

The exhibition's magnum opus depicts South American liberator Simón Bolívar as he appears on the Venezuelan currency (the bolivar, natch). Montoya laboured on it outside his Bogotá home, the only space large enough to spread the canvas, propping a projector on stacks of furniture and using real petroleum as his ink. In Bolívar's pupils, you can just make out the contour of an oil derrick.