the new technique of diffuse reflectance laser flash photolysis has been used to study the photochemistry of molecules, such as acridine and diphenylpolyenes adsorbed on metal oxide surfaces and electronic energy transfer between benzophenone and methylnaphtalene at interfaces. triplet-triplet absorption spectra and decay kinetics have been observed from aromatic ketones such as xanthone, butyrophenone and valerophenone included within zeolite channels and from ruthenium (ii) tris (2,2' bipyridine) both bound to polymers and within cavities of an ion exchange resin. photophysical processes within dyed fabrics e.g. aluminum phthalocyanine, eosin and erythrosin on cotton have been investigated directly for the first time. time resolved spectra following laser excitation of porous doped photoelectrodes e.g. zinc oxide doped with cobalt, have been obtained which show isosbestic points as the transient decays by electron transfer to give back co2+. keywords: alumina, diffuse reflectance, dyed fabrics, electron transfer, energy transfer, functionalised polymers, heterogeneous photochemistry, interfaces, surfaces, kubelka munk theory, laser flash photolysis, opaque materials, photochemistry, picosecond spectroscopy, semi conductors, sensitizers, silica, thermal effects, transient absorption, transient decay, triplet states. (mjm)