This paper reports on the study of ferromagnetic tunneling junctions produced by magnetron sputtering technique and deposited under oxidation conditions that lead to low potential barrier height, low asymmetrical barrier and quantum tunneling as the charge transport mechanism. The exponential growth of the effective area-resistance product with the effective barrier thickness, and the concentration of the tunnel current in small areas of the junctions, were identified by fitting room temperature I-V curves, for each individual sample, with either Simmons’ [J. Appl. Phys. 34, 1793 (1963); 35, 2655 (1964); 34, 2581 (1963)] or Chow’s [J. Appl. Phys. 36, 559 (1965)] model. This result suggests the presence of effective tunneling areas or hot spots, leading to a non-uniform current distribution and showing quantum tunneling as the charge transport mechanism. This mechanism, is also, verified through I-T curves.