A new ligand, S-benzyl-(-N-[10-ethylphenothiazinyl-3yl]-methylene] dithiocarbazate (abbreviated as HL), and its complexes ML2 (M=Co and Hg) have been synthesized and fully characterized by elemental analyses, EI-MS, 1H NMR, IR, UV-Vis spectra, and photoluminescence measurement. All of the compounds emit an olivine color in DMF solution. The emission maximum (lambdamax(em)), and fluorescence quantum (phif) of each compound were measured. Nonlinear Optical properties of the HL and ML2 were studied by z-scan technique. Nonlinear absorption coefficient beta were measured to be 0.71, 0.19 and 0.395 cm x GW(-1). Theoretical calculations (RHF/PM3) were consistent with the experimental results.