The arrangement of machines or departments along a straight line is known as single row layout and it is a widely employed configuration in flexible manufacturing systems. In this paper, a hybrid genetic algorithm (HGA) is proposed to solve the single row layout design problem with unequal sized machines and unequal clearances. The algorithm is developed by hybridisation of a genetic algorithm with a local search operator. The proposed HGA is tested on 51 well known data sets from the literature with equal and unequal clearances, and the results are compared with the best known solutions. Finally, algorithm's effectiveness in reaching previously known best solutions is revealed and improvements up to 7% in problems with unequal clearance are obtained.