A systematic investigation was carried out to determine the metastable zone width (MSZW) and induction period values of cytidine 5'-monophosphate disodium salt (5'-CMPNa2) in an ethanol + water mixture solution. Experimental determination of the MSZW was performed using a laser method. The two factors solution temperature and agitation were evaluated in this study to measure the MSZW. It was observed that the MSZWs decreased when the agitation levels increased and were little affected by solution temperature. The induction period was combined with the classical theory of nucleation. The various critical nucleation parameters, such as the interfacial tension (gamma), the radius of critical nucleus (r*), the critical free energy of nucleus (Delta G*) and the molecular number of critical nucleus (i*) were evaluated in the controlled nucleation condition. The critical nucleation parameters varied with increased temperature, and the nucleation rate increased with increased supersaturation.