Spectroscopic properties of Zn-2, ZnHe, ZnNe and ZnAr van der Waals molecules have been studied using CCSD(T) method. The spectroscopic constants are estimated from our newly developed method for calculating the spectroscopic constants of weakly bound molecule in Lennard-Jones potential. Most of the spectroscopic constants are first predicted. The equilibrium bond length, harmonic frequency and dissociation energy agree very well with the experimental values. (c) 2007 Elsevier B.V. All rights reserved.