Two-dimensional(2D) materials have become very attractive due to their novel electronic behavior after the discovery of graphene. Here, we report the electronic structure and thermoelectric properties of 2D materials (reduced graphene oxide(rGO), tungsten disulfide(WS2), molybdenum disulfide(MoS2) and their composites. For example, we report the carrier transport properties of thermally rGO (TrGO) as a function of reduction temperature. The transfer curve of a field effect transistor fabricated with TrGO exhibited ambipolar properties, and the charge neutrality point of TrGO was shifted from negative to positive as the reduction temperature increased. Seebeck coefficients of the fabricated TrGOs were calculated from the transfer curve using Mott’s equation for metallic materials and compared with the measured coefficients in TrGO bulk films. Also, the following studies on WS2 and MoS2 provide a way to tune the thermoelectric properties of 2D mateirlas in the future.