Nigeria is witnessing significant increase in energy demand as a result of rising population and economic growth; as more focus on clean energy take hold. These challenges have triggered the search for shale gas and shale oil in the inland basins of Nigeria. The aim of the study is to carry out an integrated study that incorporates petroleum systems modelling, field studies and advanced analytical programs in order to define the hydrocarbon prospectivity of Upper Cenomanian-Lower Turonian Eze-Aku Shale and Ekenkpon Shale as potential shale gas/oil plays in southeastern Nigeria. Available subsurface information which includes exploration wells and proprietary Oil Company archive data were used to calibrate and simulate 1-D basin models. Amount of silica content, major clay mineral group and microfabric of the potential shale resource plays were determined using Energy Dispersive X-ray Fluorescence analysis, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy respectively. The simulated models showed that deeply buried Eze-Aku Shale and Ekenkpon Shale have undergone episodic generation of hydrocarbon. Significant amount of silica content (>30%) in Eze-Aku and Ekenkpon Shale samples suggested a brittle nature of the samples and the possibilities of the samples to capture portion of expelled hydrocarbon. Identification of non-swelling clay mineral group in the analyzed shale samples indicated that the samples have the potential for shale gas/oil. The SEM images of analyzed samples showed differences in cementation. This study recommends that deeply buried Eze-Aku Shale and Ekenkpon Shale are potential exploration targets for shale gas/oil in Abakaliki Fold Belt and Calabar Flank of the southeastern Nigeria.