Nanoscale grain-size tantalum films with tetragonal crystalline structure were prepared on BK7 glass and 304 steel by low power direct current magnetron sputtering at room temperature. Effect of deposition time on structural and electrical properties of tantalum thin films has been investigated. In all cases, highly preferred (330) orientation can be observed in X-ray diffraction measurements. With increasing the thickness of deposited films from 152 to 388nm, a weak X-ray photon peak is diffracted from (720) planes of -Ta. The atomic force microscopy micrographs show the grain size of 2030 and 100140nm for films deposited on glass and steel substrates respectively. Deposition rate was approximately constant. The resistivity of samples on glass substrate is decreased with increasing the time of deposition. Transmittance of deposited films on glass substrate is decreased with increasing the thickness of sample.