We presented for the first time an abundance analysis for the system and found results in agreement with those for B stars in the solar neighbourhood for both components. This analysis led to a systematic uncertainty of some 500 K for the effec-tive temperatures of the components. Thus, these two parameters of this seemingly well-known system remain uncertain despite our detailed analysis based onéchelle spectroscopy. It is not uncommon to find systematic uncertainties and deviations between photometrically and spectroscopically derived effective temperatures of B-type stars (e.g. De Ridder et al. 2004 for a discussion), and even to have uncertainties of order 500 K for such stars among methods based on the same **data** (e.g. Smalley & Dworetsky 1995, Morel et al. 2006, Kaiser 2006. Previous works on CV Vel did not include a spectroscopic temperature estimate and were thus not able to estimate the systematic uncertainty of the component's temperatures.