Two different complexes of copper(II) propionates, [Cu2(C2H5CO2)4] (1) and Na[Cu4(C2H5CO2)9(H2O)3] (2) have been isolated from the reaction of Cu(II)(NO3)23H2O with propionic acid in an aqueous solution of NaOH. X-ray structural analysis revealed that complex 1 consists of a one-dimensional chain of an apical-to-basal CuOCu linkage of pairwise binuclear anhydrous cupric propionates, which agrees with results previously reported. Compound 2 consists of a cation Na+ which interacts with six oxygen atoms of carboxylate groups, and anionic [Cu4(C2H5CO2)9(H2O)3]− ion, which contains one isolated syn-syn-carboxylato dimeric copper(II) complex [Cu2(C2H5CO2)4(H2O)2], and a linear chain containing one syn-syn-carboxylato dimeric [Cu2(C2H5CO2)4] and its apical position linked by a carboxylate bridge with a unit of [Cu(C2H5CO2)(H2O)]. Cryomagnetic susceptibilities 1 and 2 have been measured over the temperature range 4–300 K. In 1, the spins are coupled through an alternating one-dimensional antiferromagnetic interaction. In 2, the cryomagnetic exchange interaction has been interpreted in terms of a strong antiferromagnetic interaction associated with the two paired dinuclear units of Cu(II) ··· Cu(II), and one mononuclear Cu(II) unit which complies with a Curie-Weiss law.