A novel Ca(II) coordination polymer, [CaL₂(H₂O)₂]_n (1, HL = 4-acetylphenoxyacetic acid) has been synthesized with 4-acetylphenoxyacetic acid, Ca(ClO₄)₂·4H₂O and NaOH as raw materials. Complex 1 was characterized by elemental analysis and single-crystal X-ray diffraction analysis. The results show that the Ca(II) ion is eight-coordinated in a distorted triangular dodecahedral geometric configuration with six carboxylate O atoms of four L ligands and two O atoms of two coordinated water molecules. Complex 1 forms a one-dimensional chained structure by the bridging effect of carboxylate O atoms. The antitumor activity of HL ligand and complex 1 has also been investigated.