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 ( \varpi = 60 \pm 2 degrees ) shows a variation with respect to previous studies .
We have determined the apsidal motion rate of the system \dot { \varpi } = 12.1 \pm 0.3 \degr yr ^ { -1 } , which was used to calculate the absolute masses of the binary components : M _ { 1 } = ~ { } 22.5 \pm 1.0 ~ { } M _ { \sun } and M _ { 2 } = 20.5 \pm 0.9 ~ { } M _ { \sun } .
Analysing the separated spectra we have re-classified the components as O7V z and O7.5V z stars .