In previous studies we demonstrated that SOI MESFET device structure is a suitable candidate for micropower circuit applications due to its high anticipated cut-off frequency . Even though the device offers higher f T, there is no guarantee that minimum device dimension will offer optimum performance in terms of voltage gain. To examine this issue, we developed a transport model, based on the solution of the Boltzmann Transport Equation, for modeling n-channel silicon-on-insulator (SOI) MESFETs using the in-house Ensemble Monte Carlo device simulator. From the simulations it is observed that the optimum device exhibits 33.3GHz cutoff frequency and 25.3 voltage gain. From this analysis we may conclude that the SOI MESFET device structure is a suitable candidate for application in r.f. micropower circuit design and there exists a device structure with a particular doping, silicon film thickness and gate length that shows optimum high frequency performance in terms of cut-off frequency and voltage gain.