In the field of laser processing, traditional applications have centred on thermally induced physical reactions, such as trimming, alloying, drilling, annealing, etc. The authors briefly introduces and reviews the various uses of intense photon beams to induce localised or large-area chemical reactions. The major modes of laser chemical processing are discussed, and reactions leading to etching, deposition and surface modification of microelectronic materials are described. Recent developments and future possibilities for application are also briefly summarised.