Abstract The integration of process heat with regenerative steam Rankine cycles by preheating the boiler feedwater increases power generation from the steam turbines. In oxy- combustion coal based power plants, considerable compression heat from the air separation unit is available for such heat integration, however, there are at least two challenges: (1) how to integrate a heat stream with the steam cycle, and (2) how to optimize the compression scheme. This paper investigates the mentioned heat integration by building Mixed-Integer Nonlinear Programming (MINLP) models. Two special cases (adiabatic compression and “isothermal” compression) are also investigated to compare with the optimization approach. The results show that the thermal efficiency of the reference power plant increases by a maximum of 0.5–0.6 % points. The integration is less attractive when the temperature difference of the heat transfer between the compressed gas and the boiler feedwater is larger than 40°C.