You should have a plausible reason justifying your guide change during your Ph.D. at IIT Kharagpur. One such reason can be very slow progress or laid back attitude. There might be any other compatible issues as well that might hinder your progress in getting the required training for a Ph.D. degree. Once you are certain that your reason is one that needs to be addressed, present your stance to your Head of the Department, who will call a meeting of your doctoral scrutiny committee (DSC). You will be asked to present the case in front of the DSC members and your guide who has to agree to release you from his guidance. Once you have been released, another faculty member of the same department should volunteer to take you under his umbrella. Concludingly, there are 3 major requisites for Ph.D. guide change A concrete reason like no progress The faculty guide should be ready to release you happily Another faculty guide should be ready to take you under his guidance. These may look like simple steps but sometimes can be very difficult and challenging.