An attempt was made to develop new phase change materials (PCMs) for cold heat storage at 278-293 K. The melting temperature and the latent heat of new PCMs composed of trimethylolethane (TME) trihydrate and 5-30 wt% of organic or inorganic additives were evaluated by differential scanning calorimetry. As the results, the following findings were obtained; 1. The melting temperature of TME trihydrate decreased with the increasing amount of additive, irrespective of the species of additive employed. 2. TME trihydrate with the addition of NaCl, KCI, CaCl2, NH4Cl, NaNO3, KNO3, CH3COONa and urea was considered as a potential PCM for cold heat storage at 286-300K. The melting temperature of TME trihydrate with the addition of more than 15 wt% of urea was 17 K lower than that of TME trihydrate, with the decrease in the latent heat value of 27% less than that of TME trihydrate. 3. One of the PCMs whose melting temperature was lowered by urea, the mixture of TME/H2O/urea at the mixing weight ratio of46.9/28.1/25.0, was found to be non-corrosive to aluminum and stainless steel.