The ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (bmim-PF6) has been used as solvent for a series of representative photochemical reactions covering energy transfer, hydrogen transfer and electron transfer. Low oxygen solubility, slow molecular diffusion, enhancement of the triplet excited state and radical ion lifetimes and weakening of the CT interactions are the major characteristics featured for this ionic melt. (C) 2002 Elsevier Science B.V. All rights reserved.