4-(R-Phenylazo)-2-methyl quinoline derivatives form (1:1) complexes with nickel chloride, nickel acetate and copper acetate which were syntheses. The three complexes are non-electrolyte in dimethylsulfoxide (DMF). The results of electronic and magnetic measurements show that these complexes are of octahedral structures. The oxygen and nitrogen donate their lone-pair electrons to metal ion to form chelates with formula [MLR_m^.nH₂O]. The relative stabilities of the complexes have been calculated from TG curve using Coats-Redfern and Ozawa methods.