Schiff bases in general are important molecules from several aspects. They are compounds with a functional group that contains a carbon-nitrogen double bond with the nitrogen atom connected to an aryl or alkyl group, not hydrogen. Imines are crucial synthetic intermediates, they do have biological role and the salicylidene types may exibit thermocromic or photocromic properties. These latter two are connected to structural features, i.e., to the possibility of proton transfer complex formation. In this work, the Z-Scan technique is used to measure the nonlinear optical properties of p-bromo-benzylidene aniline substituted. All compounds display absorption bands in the range between 250 and 440 nm, being transparent in the near infrared region. Under 405 nm milliseconds excitation, the nonlinear optical process of p-bromo-benzylidene aniline substituted in DMSO solutions is caused by laser heating. The optical nonlinearity is proportional to the value of linear absorption and depends on substituent and his position.