This study investigated the electrical properties of Mg-Al co-cloped Ba0.5Sr0.5TiO3 (BSTMA) films, fabricated on a P-type Si (100) substrate by a sol-gel spin coating process. Pt electrodes were deposited by radio frequency magnetron sputtering to form metal-insulator-metal capacitors. The current-voltage characteristics of the BSTMA films were also studied for various external electric fields and temperatures. Experimental results indicate that the leakage currents of Mg-Al co-doped BST films are lower than those of Mg-doped specimens. The leakage currents of 5 mol% Mg-doped and 5 mol% Mg-5 mol% Al- co-cloped BST films are 1.14x10(-3) and 1.56x10(-5) A/cm(2), respectively, at 805.5 kV/cm and 298 K. The current-voltage characteristics are ohmic behavior in the lower field region (E <= 32 kV/cm) followed by Schottky emission transport behavior in the higher field region (32 <= E <= 604 kV/cm). While at high field (E <= 604 kV/cm), both the Schottky emission and Poole-Frenkel transport behavior are observed. The Schottky emission barrier height and Poole-Frenkel trap depth level depend on the applied electric field and the temperature at which the measurements are made. (C) 2008 Elsevier B.V. All rights reserved.