The paper sums up the results of observations made during the commissioning of the roller press (RP) for slag grinding for TISCO cement project. At the time of selection of the RP technology for this project, then was not adequate experience available in regard to the process and design parameters leading to series of problems during start up acid commissioning. This necessitated examination of various parameters. It has been established that the feed arrangement to the RP, moisture in feed slag and the roll-speed are critical factors in achieving a stabilised and efficient RP operation. The process is inherently prone to build-up of iron concentration in the grinding circuit from a very small percentage in the feed slag which needs to be taken care of during the process.