The ligand 4-(4'-phenyl-2'-thiazolylazo)-resorcinol (L) was prepared. The ionization constants of the ligand (pK(a)) and the stability constants of the complexes with Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) have been estimated spectrophotometrically and pH-metrically at 298 K. The effect of some organic solvents and pH on the absorption spectra of the ligand and its complexation with the cations above was studied and discussed. The use of this ligand for spectrophotometric determination of the cations under investigation was also studied. Stoichiometric complexes with ratios 1:1 and 1:2 (M:L) were formed for all cations used except Cd(II) which forms only a 1:1 stoichiometric complex. Also, a conductometric study has been carried out, and the results show that the same stoichiometric complexes have formed in the solution.