AbstractA study has been made of the rate of formation of estolides from castor oil fatty acids and of their decomposition at different temps. Estolide formation appears to be optimum at the end of 5 hr at about 220C, beyond which estolides start decomposing, giving rise to DCO fatty acids. At about 300C, estolide decomposition is complete within an hour.During estolide formation there is a linear increase in optical rotation which again decreases linearly, although at a different rate, during estolide decomposition. At optimum estolide formation, the optical rotation is as high as 25.5.