This paper presents an adaptive rate of change of frequency (ROCOF) based passive Islanding detection technique (IDT) to overcome the problem and limitation of other techniques. The proposed ROCOF based passive IDT relies on the settings of the phase lock loop (PLL) closed loop control system for frequency, ROCOF and threshold ROCOF value for the PCC relay calculations, which measures at the PCC in the system. The adaptive ROCOF based IDT is developed and implemented on the different types of the microgrid systems such as (i) generator based microgrid (ii) generator, PV and storage based hybrid microgrid in Matlab/SimpowerSystem. Results show that the proposed IDT successfully detected the islanding condition even on zero power mismatch and it is fully capable to distinguish between islanding (loss of mains and external fault) and nonislanding (internal fault) condition with a diverse range of operating conditions.