Irradiation of Donor-Acceptor systems often leads to the formation of radical cation-radical anion pairs (via photoinduced electron transfer) and subsequent ground state reactions of these ion pairs can give rise to reaction products. We have been partlclarly interested in two electron deficient aryl halides 3,4, 5,6-tetrachlorophthalonitrile (TCPN) and 3,4,5,6-tetrachloro-N-methylphthalimide (C14NMP) as possible electron acceptors in such photoinduced electron transfer reactions. Their photochemical reactions with various potential donor molecules (including several aromatic hydrocarbons and a range of alkenes) have been studied. Several different modes of reactivity were observed and these have been discussed in relation to a possible electron transfer mechanism being operative.