Phenylthiazol-2(3h)-ylidene-isoquinoline-5-amine derivatives(5a-r) were easily prepared from 5-aminoisoquinoline, thioisocyanate, and phenacyl bromide derivatives in the presence of triethylamine in tetrahydrofuran (THF), and dimethyl formamide (DMF) in two steps. In the first step, thiourea was synthesized in THF reflux, 24 h and then in the second step, the formation of thiazole ring was ensured in EtOH-DMF (5:5 v/v), reflux, 24 h. The newly synthesized compounds were characterized using 1H NMR, 13C NMR, IR, and elemental analysis. The inhibitory effects of 18 newly synthesized compounds (5a-r) on hydratase and esterase activities of carbonic anhydrase isoenzymes (hCA I, II, IX, and X) were studied in vitro.