Two copper(II) complexes, [CuL2(EA)] (1) and [Cu2L4(PA)2]·2H2O (2·2H2O), where L is 1-naphthylacetate, EA is N,N-diethylethane-1,2-diamine, PA is propane-1,3-diamine, have been prepared and characterized. Structures of the complexes have been characterized by single-cyrstal X-ray diffraction. Complex 1 is a mononuclear copper(II) compound, with the Cu atoms coordinated in square planar geometry. Complex 2·2H2O is a centrosymmetric dinuclear copper(II) compound, with the Cu atoms coordinated in square pyramidal geometry. Single crystals of the complexes are stabilized by hydrogen bonds. The effects of the compounds on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans, as well as thermal behavior of the complexes were studied.