The influence of Cr deposition on the magnetic properties of epitaxial Co films grown on a Pd(111) single-crystal is analyzed by in situ magneto-optical Kerr effect measurements. Auger electron spectroscopy and low-energy electron diffraction are used for monitoring the growth and structure of the films. Co films thicker than 0.5 monolayer (ML) exhibit a ferromagnetic order at room temperature. In the case of uncovered Co films grown on Pd(111), the easy magnetization axis is found to be perpendicular for thicknesses between 1.1 and 2 ML, and in plane above. Covering thin Co films with Cr layers produces a non-monotonous variation of the coercive field and normalized remanence, and a reorientation of the easy magnetization axis from in plane to out of plane.