The formalism based on the total energy bifunctional ͑E͓ I , II ͔͒ is used to derive interaction energies for several hydrogen-bonded complexes ͑water dimer, HCN-HF, H 2 CO-H 2 O, and MeOH -H 2 O͒. Benchmark ab initio data taken from the literature were used as a reference in the assessment of the performance of gradient-free ͓local density approximation ͑LDA͔͒ and gradient-dependent ͓generalized gradient approximation ͑GGA͔͒ approximations to the exchange-correlation and nonadditive kinetic-energy components of E͓ I , II ͔. On average, LDA performs better than GGA. The average absolute error of calculated LDA interaction energies amounts to 1.0 kJ/ mol. For H 2 CO-H 2 O and H 2 O-H 2 O complexes, the potential-energy curves corresponding to the stretching of the intermolecular distance are also calculated. The positions of the minima are in a good agreement ͑less than 0.2 Å͒ with the reference ab initio data. Both variational and nonvariational calculations are performed to assess the energetic effects associated with complexation-induced deformations of molecular electron densities.