We analyze the cluster properties and investigate the galaxy population of a sample of low-luminosity X-ray galaxy clusters at intermediate redshifts (z = 0.2 - 0.5). The study is based on deep imaging and spectroscopic observations and X-ray archival data. We discuss in detail the global cluster properties and galaxy content based on the analysis of the velocity distribution, the galaxy projected distribution, the cluster color-magnitude diagram, and the study of the mass distribution, based on weak lensing and X-ray emission, for one of the cluster located at z = 0.485.