BiFeO3 (BFO) thin films were grown epitaxially by rf oxygen plasma assisted molecular beam epitaxy on SrTiO3 (001) substrates with and without SrRuO3 (SRO) thin film electrodes. BFO thin films show excellent crystalline quality and x-ray diffraction studies show the presence of only one phase. Polarized Raman spectroscopy also confirmed high crystalline quality of the films. BFO thin films show presence of ferroelectricity on conducting Nb:STO substrates and SRO-STO. Films on Nb:STO have leakage currents similar to 0.1 mu A/cm(2) and remnant polarization similar to 28 mu C/cm(2). Films on SRO-STO have leakage currents similar to 8 nA/cm(2) and remnant polarization similar to 56 mu C/cm(2). Nb diffusion and poor surface quality of Nb:STO can be attributed to the difference in ferroelectric and leakage properties of the BFO thin films grown on Nb:STO and SRO-STO. (c) 2007 American Vacuum Society.