Results of calculations of high voltage electron cooling process in NICA collider are presented. Two independent electron cooling systems in the collider are intended to increase luminosity in space charge dominated regime. The model of cooling calculations was tested on experimental results, obtained in COSY synchrotron, which is equipped with 2 MeV electron cooler, produced by Budker INP. Also a project of high voltage electron cooling systems for the NICA collider is presented.