The standard (po = 0.1 MPa) molar enthalpies of formation for crystallin 3-, 5-, 6-, and 8-aminoquinoline were derived from the standard molar enthalpies of combustion, in oxygen, at the temperature T = 298.15 K, measured by static-bomb combustion calorimetry; the Knudsen mass-loss effusion technique was used to measure the vapour pressures of the crystals as functions of temperature, and the standard molar enthalpies of sublimation, at the temperature T = 298.15 K, were derived by the Clausius-Clapeyron equation. Direct measurements of the standard molar enthalpies of sublimation, using microcalorimetry, for 3- and 5-aminoquinoline, confirmed the values from the Knudsen technique. [[formula]]. © 1993 Academic Press Ltd.