The mixture of lauric acid and capric acid is a potential latent heat storage material. However, its eutectic melting temperature is quite high for low-temperature thermal energy storage. Addition of naphthalene is proposed. The ternary system lauric acid-capric acid-naphthalene has been investigated by differential scanning calorimetry (DSC), visual polythermal and chromatography of gases. The phase diagram is of an incongruent eutectic type. The eutectic mixture contains 18.4 mol% lauric acid, 63.1 mol% capric acid and 18.5 mol% naphthalene and melts at 13.3 degreesC; The peritectic mixture contains 32.4 mol% lauric acid, 48.2 mol% capric acid and 19.4 mol% naphthalene and peritectic temperature of 16.2 degreesC. The incongruent compound was analysed to be CH3(CH2)(10)(COOHCH3)-C-.(CH2)(8)COOH. The melting temperature of the lauric acid-capric acid-naphthalene eutectic mixture makes it suitable for cooling applications. (C) 2004 Elsevier B.V. All rights reserved.