This thesis deals with the operation problems of automated guided vehicle (AGV) which can be used as either carrier or mobile workstation mode in flexible production lines. The aim is to minimize the production makespan. Under mobile workstation mode, an optimal sequence of the loads and the successive lunch times are determined simultaneously with the branch and bound technique. Also, the operation problems of a single carrier AGV are studied for two cases, one with no queue and the other with single capacity queue permitted in each workstation.