A detailed study of thermal vacancies in Pt by positron lifetime spectroscopy yields the vacancy formation enthalpy H 1VF = (1.35 ± 0.09) eV and the positron lifetime τ1V = 168 ps in monovacancies. The tentative fit of a model that includes mono‐ and divacancies yields an estimate of the divacancy binding energy H 2VB = (0.5 ± 0.4) eV and a positron lifetime in divacancies τ2V = 174 ps which only slightly exceeds τ1V. The present value of the vacancy formation enthalpy H 1VF is discussed in conjunction with the results of quenching experiments. A comparison with self‐diffusion data yields the vacancy migration enthalpy H 1VM = 1.34 eV which is in agreement with attributing the annealing stage at 600 to 650 K, observed after electron irradiation, to long‐range migration of monovacancies.