Carbon dioxide adsorption behavior and sorption kinetics of two shales from Damodar valley basin, India were experimentally investigated by volumetric method at 313 K and up to 6 MPa. Langmuir, Dubinin-Astakhov, Dubinin-Radushkevich and Brunauer-Emmett-Teller equations were used to model experimental adsorption data. The present study was also aimed at characterizing pore-structure and composition of shale samples. The two shales were found to be rich in organic matter with total organic carbon content to be more than 5 indicating fair to good source rocks. Modeling of CO2 adsorption data showed that BET and D-A models gave better fit compared to Langmuir model. Pore volume data obtained from mercury intrusion capillary porosimetry is consistent with that of low pressure (N2 and CO2) adsorption for pore sizes > 10 nm for SLP sample. In case of PAK sample, pore size data obtained from mercury intrusion and low pressure adsorption drifted apart for pore sizes >10 nm. PAK shale displays pore structure in mesopore range with modes approximately at 3 nm and 4 nm. The SLP sample has bimodal pore structure with one peak in micropore range (SLP � 1.17 nm) and other peak at � 4 nm (mesopore range). The CO2 diffusivity determined from adsorption rate data measured at subcritical pressures was in the range of 1.0364 � 10�8 to 2.6588 � 10�8 for PAK shale and 1.0624 � 10�8 to 1.6343 � 10�8 for SLP shale. Further, it can be suggested that during initial time, CO2 diffusion in shale is a non-steady process and later transforms to steady-state mechanism. © 2019 Elsevier B.V.