Kunigel-V1 (KV1) bentonite samples were cured at 130, 200 and 300°C for 30, 60, 120, 240, 480, 1000, and 1500 days to grant them different temperature histories. Swelling strain and swelling pressure tests were conducted to obtain their equilibrium swelling strains (ε_eq) and equilibrium swelling pressures (p_eq), respectively, to evaluate high-temperature history effects on KV1 swelling characteristics. Subsequently, cured KV1 samples underwent methylene blue adsorption (MB), cation exchangeable capacity (CEC) and leached cation (LC) tests. These tests showed the followings: 1) the temperature history affected ε_eq, but p_eq was not affected; 2) MB and CEC were not affected by the temperature history, which suggests that the montmorillonite amount in KV1 was not affected by the temperature history; and 3) limited effects were found from the effect of temperature history to leached Na⁺,Mg²⁺, and K⁺ concentrations. However, the temperature history strongly affected the leached Ca²⁺ concentration. Moreover, temperature history effects on the minerals in KV1 were discussed carefully to elucidate temperature history effects on swelling characteristics.