High Mass X-ray binaries (HMXB) with black hole companions represent a key intermediate stepin the binary black hole formation channel. Detailed knowledge of the stellar and wind parameters of thedonor is essential to understand the complex behavior of such systems. Our current understanding of wind ofmassive stars in black hole binaries is mostly based on Cygnus X-1 in our Galaxy and was not analyzed bymeans of sophisticated stellar atmosphere models. In this study, we carried out a detailed analysis of windsof doner star in M33 X-7 as well as a re-analysis of Cygnus X-1. M33 X-7 is the only known eclipsing blackhole binary with a very massive O supergiant donor and one of the most massive black holes known in anHMXB. In this talk, I will present a detailed spectroscopic analysis (Xray+UV+optical) of the massive donorduring different orbital phases. This sheds light on the stellar and wind parameters of the metal-poor donorstar. The observed properties are compared with detailed binary-evolution tracks to constrain the possibleformation channel and evolutionary fate of the system.