In this study we developed a composite mesoporous honeycomb element based on Wakkanai siliceous shale (WSS) and lithium chloride (Lid), to act as a thermal energy storage medium that can directly contact the functional air in an open sorption thermal energy storage system. The mesopores of the WSS were filled with LiCl to improve its sorption capability as a new sorption thermal energy storage material. The honeycomb thermal energy storage element impregnated with 9.6 wt% LiCl was installed in the developed open sorption thermal energy storage experimental setup. The experimental results showed that this impregnated honeycomb element could be regenerated at a lower regeneration temperature, even at 60 degrees C, and also exhibited high volumetric heat storage density. Furthermore, at a certain regeneration temperature, the element impregnated with 9.6 wt% LiCl supplied air with a relatively constant high outlet air temperature compared to the element filled with 22.4 wt% CaCl2 under the same inlet air conditions in the sorption process, and the proposed element was less affected by the humid air flow rate. The sorption rate was observed to significantly affect the outlet air temperature during the sorption process. We confirmed that the developed composite material filled with LiCl exhibited good stability, boosting the possibility of its long-term use. (C) 2014 Elsevier Ltd. All rights reserved.