Magnetization and specific heat measurements have been performed for the S = 3/2 antiferromagnet on a kagome staircase, Co3V2O8 single crystal as a function of temperature and magnetic field. Using these data the phase diagram was established on the H-T plane and compared with that determined for Ni3V2O8. The both phase diagrams are described by a model of competing first and second neighbor interactions and uniaxial anisotropy with the easy-axis magnetization along the a-axis. (c) 2006 Elsevier B.V. All rights reserved.