This study investigates the potential of "methanol + acetaldehyde <--> hemiacetal" as a liquid phase thermoreversible reaction for long-term storing of low-grade thermal energy to overcome the mismatch between energy supply and demand. Both forward and backward reactions are studied experimentally and the technical issues associated with employing such a system are discussed. Methanol and acetaldehyde would react via an exo- thermic reaction (-Delta H-r = 31.8 kJ/mole or 104.7 kWh/m(3)) at low temperature range ( < 15 degrees C) and atmospheric pressure, with a high reaction rate (k = 26.26 x 10(2)exp(-4099/T)). The regeneration of parent reactants with high purity occurs at 48 degrees C which can easily be delivered using low-grade heat. The low operating temperature required for forward reaction and the reduction in backward reaction rate caused by methanol accumulated are the main engineering challenges. These technical problems need to be solved before this reaction could be utilised commercially.