(Solid + liquid) and (vapour + liquid) equilibria for the binary systems (propane + adamantane) and (ethane + adamantane) were determined according to the synthetic method in the temperature range 300-510 K and in the pressure range 0.3-10 and 0.3-180 MPa, respectively. For both systems also the three-phase curve (solid adamantane + liquid + vapour) was determined and some vapour-liquid critical points at low mole fractions of adamantane. In the case of (propane + adamantane) the three-phase curve (solid adamantane + liquid + vapour) is continuous and shows a pressure maximum at a temperature higher than the critical temperature of propane. In the case of (ethane + adamantane) the three-phase curve (solid adamantane + liquid + vapour) is split into a low-temperature branch which runs from low temperature with a positive slope dP/dT to higher temperature and ends at a first critical endpoint at T = 309.55 K and P = 5.17 MPa. The high temperature branch of this curve starts at the second critical endpoint T = 432.65 K and P = 15.85 MPa, runs to higher temperature with a negative slope dP/dT and ends at the triple point of adamantane. (C) 2004 Elsevier B.V. All rights reserved.