The effect of substituent on the  photophysics of D-A-D molecules, bis(4-dimethylaminophenyl) squaraine and its derivatives (1-17) has been studied in methylene chloride and chloroform. The fluorescence lifetime data indicate that rotation of the C-C bond between the phenyl ring and the four membered ring is the major radiationless decay process for the excited states of squaraine. While OH substitution at C-2 increases the lifetime due to the rigidization effect resulted from an intramolecular H-bonding, other C-2 substituents generally induce non-planarity in the squaraine chromophore because of the steric effect and shorten the lifetime of the excited state. Introduction of asymmetry in the D-A-D structure has very little impact on the spectroscopic and photophysical properties. Pseudo unsymmetrical squaraines USq1-USq12 are found to exhibit multiple fluorescences, monoexponential decays and similar substituent effects. The similarity in properties is consistent with that predicted by MO-calculations which show that the donor groups in squaraine do not play any significant role in the S₀ → S₁ transition. The substituent effects in pseudo unsymmetrical squaraines are consistently smaller than those observed in symmetrical squaraines, presumably due to the fewer substituents in the unsymmetrical structure.