Cu2ZnSnSe4 (CZTSe) films were prepared by selenization of oxides nanoparticles. A novel densification method was performed to improve the grain size and morphology of the CZTSe films. From absorption spectroscopy measurement, it was also found that the compressed CZTSe films showed Kesterite structure with a band gap of 0.92 eV, while the untreated CZTSe films showed partially disordered Kesterite structure with a band gap of 0.86 eV. The phase transition during the selenization of oxides nanoparticles is affected significantly by the compact density. The nucleation and growth of Kesterite phase is considered to be facilitated by the mass transfer around the particle contacts. The different characterization techniques show that the dense CZTSe layer with very large grain size can be achieved by using compression method. (C) 2013 Elsevier Ltd. All rights reserved.