Cu2ZnSnS4 thin films were fabricated by one-step RF magnetron sputtering of a single quaternary Cu2ZnSnS4 (CZTS) chalcogenide target on corning glass substrate, followed by annealing at 523, 623 and 723K under nitrogen atmosphere for 60 minutes. Optical transmittance and reflectance data of the films were utilized to compute the absorption coefficient, refractive index, extinction coefficient and optical band gap energy of the films. The nature of the optical transition has been direct allowed with average optical band gap energies ranging between 1.5 eV and 2.4 eV. The optical band gap energy has a tendency to increase with the increase in the annealing temperature. The resistance and sheet resistance of the films ranges from 4.1 -3Ω cm-14680 -3Ω cm and 0.02 3Ω-0.25 3Ω respectively.