The present study presents the magnetocaloric effect (MCE) properties of Ni-rich Ni50-xCoxMn38Sn12B3 (x = 0, 1, 3, 5) ribbons during both heating and cooling processes. The Co substitution caused an increase of magnetization difference Delta M and hence an improvement of the MCE. An inverse giant magnetocaloric effect (IMCE) and a high effective refrigerant capacity RCeff were observed in the x = 3 ribbons. A high amount of Co (x = 5) content led to an inverse magnetic entropy Delta S-M peak with a wide temperature range. Magnetostructural coupling over a wide temperature range is of great importance for technological purposes. On the other hand, the MCE properties were thermal hysteresis dependent, which has to be considered in the technological applications.