[en] The technique of Translational Energy Spectrometry (TES) has been used to study electron capture processes for a number of ion-atom and ion-molecule collision systems at energies < 1 keV/amu. The systems studied were: He²⁺ ions in H₂ and CO; helium-like C⁴⁺, N⁵⁺ and O⁶⁺ ions in H and H₂; and hydrogen-like C⁵⁺, N⁶⁺, and O⁷⁺ ions in H and H₂. For each system, the main reaction channels have been identified, and in most cases, their relative importance assessed. For He²⁺ ions in H₂ and CO, dissociative one-electron capture processes have been found to account for almost 100% of the total one-electron capture cross at low energies. Dissociative one-electron capture processes were also observed in the C⁵⁺+H₂ and O⁷⁺+H₂ systems. However, in the case of N⁵⁺+H₂, two electron capture into autoionising states of N³⁺ with subsequent N⁴⁺(n=2) formation was found to be an important process at low energies, accounting for approximately 50% of the total electron capture cross section at 214 eV/amu. Dissociative capture processes were not found to be important for C⁴⁺, N⁶⁺, and O⁶⁺ systems. In the case of electron capture from an atomic hydrogen target, capture was found to occur predominantly into n=4 levels for the N⁵⁺, N⁶⁺, C⁵⁺, and O⁶⁺+H systems. For the C⁴⁺+H system, C³⁺(n=3) formation was found to be the dominant reaction channel, with O⁶⁺(n=5) formation the favoured reaction channel in the O⁷⁺+H system. Total charge-changing cross sections have also measured for the N⁵⁺+H₂ system using a simple beam attenuation method. While agreeing with previous PES measurements in the region of overlap, the measurements are in poor agreement with OPIG measurements and theoretical calculations. For some of the systems studied, Landau-Zener and classical over-barrier reaction-windows have been calculated. For N⁵⁺, O⁵⁺, and C³⁺ ions colliding with H and H₂, agreement with the present results was found to be good