A new sorbent for warm CO2 capture containing magnesium oxide was developed using incipient wetness impregnation. The reversible adsorption isotherm, cyclic stability, and sorption rate were measured using a custom-built high-pressure microbalance system and a thermogravimetric analyzer. The experimental data indicate that the sorbent has a fairly large regenerable capacity in the 180-240 degrees C temperature range, fast kinetics, low heat of adsorption, and stable working capacity for at least 84 cycles. The new sorbent performs better than synthetic hydrotalcite and K2CO3-promoted hydrotalcite in the temperature range of interest. This makes the sorbent a very promising candidate material for warm CO2 capture by pressure swing adsorption.