The novel microporous mixed-transition-metal phosphate Zn2Co4(PO4)(4)(H2O)(5).2H(2)O has been synthesized hydrothermally and structurally characterized by single crystal X-ray crystallography. It has a new open-framework structure containing unusually large ellipsoidal cavities which are connected with each other through 10-ring openings to form channels parallel to the a axis. The thermal and magnetic properties of the compound ale also presented.