The enzyme firefly luciferase was patterned onto gold and glass surfaces at micrometre resolution using a novel photopatterning technique. The bioluminescence emitted on addition of the enzyme substrates luciferin and ATP allows these patterns to be visualised. Electrical switching of enzyme activity has been achieved by using enzyme immobilised on a gold surface as one electrode in an electrolysis cell, These techniques have applications in biosensor construction and in bioelectronics.