A porphyrin-fullerene covalently linked dyad is studied in solutions and Langmuir-Blodgett (LB) films. The dyad is characterized by a relatively long linker. In benzonitrile, it performs a relatively slow photo-induced electron transfer (ET), k(ET) approximate to 5 x 10(8) s(-1). Being incorporated in an LB film the dyad forms a compact conformer, which takes the smallest surface area. For this conformer the donor-acceptor separation is much shorter as compared with that in liquid phases and the molecule perform a fast photo-induced ET, k(ET) approximate to 8 x 10(9) s(-1). The LB films were studied using time-resolved measurements of fluorescence, absorption, and Maxwell displacement charge. (C) 2002 Elsevier Science B.V. All rights reserved.