The beam coherence-polarization (BCP) matrix contains its elements in the form of mutual coherence functions. These are complex quantities governing the space-time correlations between the x and the y components of electric field at pair of points in the cross-section of the random electromagnetic beam. In this paper, we present mathematical expressions to determine the amplitude and the phase of the four elements of the BCP matrix which are a function of two spatial points in the optical field. We also determine experimentally the BCP matrix for an expanded laser beam introducing polarizers and rotators in widely separated beam paths of a modified version of the Young's interferometer. The real and imaginary parts of the BCP matrix elements might show the change in the polarization properties of a random electromagnetic beam during its propagation. These results might be useful for astronomical measurements also.