Temperature-dependent Raman measurements of n-propylammonium chloride solutions in water, concentrated hydrochloric acid and methanol yield experimental gauche-trans enthalpy differences of 0.21 ± 0.13, 0.51 ± 0.26 and 0.37 ± 0.11 kcal mol⁻¹, respectively. Raman spectra in different aqueous solutions show that the gauche-trans equilibrium in solution is affected by the total chloride concentration. The gauche-trans enthalpy difference for CH₃CH₂CH₂NH₃⁺ is found by 4-31G ab initio calculations to be 0.26 kcal mol⁻¹.