Abstract: The visible absorption and fluorescence spectra of metallo derivatives of tetrakis- (ortho-chlorophenyl) porphin (OCITPP) and tetraphenylporphin (TPP) in the pre- sence of 2,4—dinitrochlorobenzene (DNCB) have been studied.Both the absorbance and the fluorescence intensity were found to be lower than those of metalloporphins in the absence of DNDB,indicating the formation of molecular complexes between the donor and the π accepter DNCB. Owing to the reduced molecular symmetry and steric hindrance resulted from the monochloro-substitution at the orthophenyl positions, the binding between the donor and the acceptor for metalloporphins of OCITPP series, was weakened, and hence the fluorescence of metallopophins of OCITPP series was less quenched by DNCB than metalloporphins of TPP series.