This study the dynamics of a two-stroke, hydrogen direct-injection, free-piston linear-generator engine with dual oppositely placed combustion chamber with two different motor drivers. The MOSFET driver was replaced by IGBT driver to improve the capacity of the engine system to enable the injection of higher current for initiating the combustion. The experiment was carried out using the MOSFET and IGBT drivers by motoring the engine without combustion using 3-battery and 5-battery configuration to compare the performance of the IGBT driver relative to the MOSFET driver. The result shows that the engine develops a higher in-cylinder pressure by using IGBT driver when it is running with both battery configurations. However, the engine was unstable when it is running with 5-battery configuration using IGBT driver. © 2011 Asian Network for Scientific Information.