Molecules of 2-chloro-N-(2-nitrophenyl)nicotinamide, C12H8ClN3O3, are linked by two C-H...O hydrogen bonds into a chain of edge-fused R(2)(2) (14) and (4)(4) (24) rings. In 2-chloro-N-(3-nitrophenyl)nicotinamide monohydrate, C12H8ClN3O3.H2O, the molecules are linked by a combination of N-H...O, O-H...O and O-H...N hydrogen bonds into a chain of edge-fused rings containing two distinct types of R(4)(4) (16) ring. In 2-chloro-N-(4-nitrophenyl)nicotinamide, C12H8ClN3O3, which crystallizes with Z' = 2 in space group P2(1)/n, the molecules are linked by two N-H...N hydrogen bonds into simple C(2)(2) (12) chains.