We present a new set of radial-velocity measurements of the spectroscopic binary HD 165052 obtained by disentangling of high-resolution optical spectra. The longitude of the periastron (̟ $latex \varpi $, which was used to calculate the absolute masses of the binary components: M1 = 22.5 ± 1.0 M⊙ and M2 = 20.5 ± 0.9 M⊙. Analysing the separated spectra we have re-classified the components as O7Vz and O7.5Vz stars.