Realization of the full potentials of group II-VI heterostructures for photovoltaic device applications require reliable and precise predictive band structure models that are consistent with the fundamental principles of solid state physics. In this article, the electronic band structure of Cd based group II-VI ternary/binary heterostructures are calculated using the second nearest neighbor (2 nn) sp(3)s* semi-empirical tight binding formalism including the spin-orbit coupling. Using this scheme, we investigated the interface strain effects on band structure, such as band gaps and band offsets, in pseudomorphic Cd1-xZnxTe/CdTe and Cd1-xZnxS/CdS heterostructures for the entire composition range (0 <= x <= 1). It is gratifying to report that there is excellent agreement between the model predictions and experiment. The model should be useful in designing the group II-VI based heterostructure solar cells for optimum performance. (c) 2005 Elsevier B.V. All rights reserved.