The selective separation and recovery of copper, cadmium, zinc, and nickel from a polymetallic solution with sulphide precipitation using thioacetamide have been investigated. Selective metal sulphide precipitation was studied as a function of pH, contact time, and temperature. The results showed that it was possible to separate metals by accurately controlling the pH and temperature. Below pH 2.5, copper precipitation was complete. The cadmium, zinc, and nickel selective precipitations were performed at pH of 4, 5.5, and 7.5, respectively. Temperature also had important effects on the selective separation, and metals precipitation yields increased with increasing temperature. Thioacetamide hydrolysis kinetics and its activation energies in various conditions were calculated. The metal sulphide precipitates were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the results showed that the produced precipitates had high purity.