Two new polyoxometalate-based ionic liquids, [TBTP](4)PW11VO40 and [TBTP](4)PMo11VO40, composed of ternary Keggin polyoxometalates and tetraalkylphosphonium cation have been synthesized and characterized. Their layered structures, thermal stability, conductive performance and electrochemical properties are investigated. The two compounds possess layered structures, and both can exhibit a reversible phase transformation process below 100 degrees C. Their ionic conductivities are dependent on temperature and follow the Arrhenius behavior. Cyclic voltammetry is carried out to study their electrochemical properties in organic solution. The potential values of redox waves indicate that the oxidability of [TBTP](4)PMo11VO40 is greater than that of [TBTP](4)PW11VO40.