A novel mixed oxamate copper(Ⅱ) complex \[Cu(phen)(om)(H 2O)\]·H 2O has been obtained and its structure was determined. The complex crystallizes in monoclinic, space group P2(1)/n, a= 0.845 3(0) nm, b=0.971 2(1) nm, c=1.742(1) nm, β=103.89(3)°, V=1.388(0) nm 3, Z=4, R=0.045 8. The copper atom is five-coordinated with a tetragonal pyramid geometry, the complex molecules are linked to form a one-dimensional network via hydrogen bonding. Its X-band EPR spectrum shows an unsymmetric broad signal with g-tensor value 2.12. The IR, TGA and DTA results are also reported. Thermal degradation of the complex starts at 50 ℃ to loss water.