2-Amino-2-methyl-1,3-propanediol (AMP), 2-amino-2-hydroxymethyi-1,3-propanediol (TRIS) and the mixture (AMP + TRIS, mole ratio 50:50) are being considered as potential candidates for the thermal storage of energy. The thermal conductivities have been measured with an uncertainty of +/-3% from 20 degreesC to the supermelting points of these substances by means of a calorimeter equipped with a thermistor. The experimental thermal conductivities of the substances under investigation are smoothed by fitting for different values of temperature and reported at intervals of 10 K. In addition, the solid-solid transition and melting temperatures are also determined to be 80 and 108 degreesC for AMP, 135 and 175 degreesC for TRIS and 70 and 142 degreesC for (AMP + TRIS), based on the thermal conductivity-temperature diagrams of these substances.