New photocatalytically active isostructural two-dimensional mixed metal-pyridine dicarboxylates, [M(H2O)(3)Co{C5N1H3(COO)(2)}(3)])(infinity)], M = Gd (1), Dy (2) and Y (3) have been prepared under hydrothermal conditions. The structure consists of a network of MO6(H2O)(3), CoO3N3 polyhedral units connected by the pyridine dicarboxylates forming two-dimensional layers, which are arranged in an AAAA... fashion. The photocatalytic studies on 1 - 3 indicate that they are active catalysts for the degradation of simple organic dyes, such as Remazol brilliant blue R (RBBR) and Orange G (OG) in the presence of UV light. The compounds have also been characterized by powder XRD, IR, TGA, UV-Vis and magnetic studies.