ABSTRACT This work presents a comparative study on the thermal and self-heating effects of ion-implanted MESFETs based on different compound semiconductors. The impact of self-heating effect on the drain current of the device is studied critically for different biasing arrangements. Two parameters defined as differential drain conductance (ΔGm ) and degradation factor (DF ) have been introduced and their values are calculated considering self-heating effect for devices based on different materials. Morever, the impact of self-heating effect on the cut-off frequency and maximum operating frequency of the device is studied. In addition, the impact of ambient temperature on the threshold voltage of the device is presented for different channel materials.