Even though the black shales in Peninsular Malaysia covered a quarter of the total surface area and have been overlooked for their economic potential except few workers have evaluated their thermal maturity using rock-eval pyrolysis, vitrinite reflectance analysis and illite crystallinity. According to these research works, the shales have been categorized into immature, mature and overmatured successions, which in turn dictated the exploration activities of commercially viable shale gas in the onshore Peninsular Malaysia. In this work, published and unpublished data on the scattered black shales of Peninsular Malaysia were examined to assess exploration potential of shales from various stratigraphic windows. Thus, using comparative evaluation of all the thermal history plots of the black shales from Peninsular Malaysia; areas of thermally matured source rocks are identified. According to the thermal maturation assessment; the Palaeozoic black shales in the Peninsular Malaysia have minimal generative potential for economically viable source rock for hydrocarbon, whereas the younger successions of Oligocene to Miocene have considerable potential to serve as source rocks of feasible prospect, provided permissible geological settings are met. © Published under licence by IOP Publishing Ltd.