Understanding the properties, formation, and evolutionary path of high- mass star systems is a fundamental research topic in stellar astrophysics. Under certain conditions, massive binaries form gravitationally bound compact objects capable of merging in less than the age of the Universe, producing gravitational waves detectable by observatories such as LIGO or VIRGO. Mass transfer between stars impacts on the orbital and physical properties of the system, making its study essential to understand the characteristics of gravitational wave progenitors. In this work we study the effects of mass transfer on the populations of binary compact objects and their corresponding gravitational wave production. We use the population-synthesis code SEVN (Stellar EVolution for N-body) to simulate large groups of binary systems and analyze different mass-transfer regimes.