A systematic study has been carried out to investigate the effect of formaldehyde-to-melamine molar ratio varying from 2.5 to 8, core-to-wall ratio from 1 to 4 and curing conditions used during the encapsulation process on the properties of microcapsules that contain n-octadecane as the core material and melamine-formaldehyde as the wall material. The microcapsules so obtained were characterized for their core content, encapsulation efficiency, thermal, and solvent stabilities. Using the modified encapsulation process with a formaldehyde- to-melamine ratio of 8 and core-to-wall ratio of 2, microcapsules with a high core content of (70%) and a heat storage capacity of > 160 J/g could be obtained. The capsules were found to be stable upto a temperature of 100 degrees C and also stable to cyclohexane wash. A thermoregulated fabric was also prepared by coating the capsules on a cellulose-polyester fabric to give a heat storage capacity of > 100 J/g. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 2997-3002,2009