We present photometric and spectroscopic data on the early-type binary MP Centauri .
The photometric data are analyzed simultaneously with radial velocities to derive preliminary absolute dimensions for the binary components .
Analysis of the spectra shows that the stars rotate synchronously and that the line of sight to the system crosses two kinematically sharp and well-separated interstellar reddening sources .
It is shown that MP Cen consists of a B3 primary with M _ { 1 } = 11.4 \pm 0.4 M _ { \sun } , R _ { 1 } = 7.7 \pm 0.1 R _ { \sun } and a lobe-filling B6-B7 secondary with M _ { 2 } = 4.4 \pm 0.2 M _ { \sun } , R _ { 2 } = 6.6 \pm 0.1 R _ { \sun }