Aims: We analyze new multicolor light curves and recently published radial velocity curves for close binaries QX And, RW Com, MR Del, and BD +07°3142 to determine the physical parameters of the components.
Methods: The light curves are analyzed using a binary star model based on Roche geometry to fit the photometric observations. Spectroscopic parameters, such as the mass ratios and spectral types, were taken from recent spectroscopic studies of the systems in question.
Results: Our findings provide consistent and reliable sets of stellar parameters for the four studied binary systems. Of particular interest is the BD +07°3142 system, since this is the first analysis of its light curves. We find that it is an overcontact binary of W UMa type and W subtype, and that each component has a large cool spot in the polar region. QX And is an A subtype, and RW Com a W subtype W UMa binary, and in both systems we find a bright spot in the neck region between the components. MR Del is a detached binary with a complex light curve that we could model with two cool spots on the hotter component.