The nucleation parameters, such as radius of the critical nucleus and critical free-energy change have been evaluated. Metastable zone-width and induction-period measurements have been carried out for tris thiourea zinc cadmium sulphate. The metastable zone-width studies have been carried out for different cooling rates. The induction-period measurements have been done and the critical nucleation parameters are evaluated based on the classical theory of homogenous nucleation and the results will be discussed. The interfacial-energy values for tris thiourea zinc cadmium sulphate were determined for different super saturation ratio as a function of temperature. Due to the combination of zinc and cadmium significant variation in the nucleation parameters have been achieved. (c) 2006 Elsevier B.V. All rights reserved.