Boron-doped diamond samples were exposed successively to singlet oxygen and pyrene-alkylcarboxylic acid molecules. The resulting samples were studied by photoelectrochemistry. It is shown that the expected esterification reaction indeed allowed the grafting of pyrene groups onto the diamond surface. Cathodic photocurrents have been obtained with quantum yields as high as eta = 0.29% (lambda = 351 nm, U = - 0.38 V vs. a saturated calomel electrode) in oxygen saturated electrolyte. The pyrene coverage is estimated from both photocurrent and photopotential measurements. The role of dissolved oxygen in the photocurrent generation is discussed. (c) 2005 The Electrochemical Society.