High-pressure mass spectrometric equilibrium experiments and electronic structure calculations have been carried out to investigate the energetics of the interactions of chloride ion with a series of normal alkanes and cycloalkanes in the gas phase. The structures of the complexes obtained from the electronic structure calculations provide considerable insight into the nature of the interaction between the negatively charged ion and the alkanes, which has the character of a purely ion-induced dipole interaction. The structural information also shows how the charged species affect the confirmation of the normal alkanes.