The present invention provides a heat sensitive composition, comprising a) at least one colour forming compound, b) at least one developer, c) at least one stabiliser of the formula (II) wherein R1 and R2 are independently from each other C1-C2o=cycloalkyl, unsubstituted or substituted aralkyl of from 7 to 10 carbon atoms or unsubstituted or substituted phenyl, R¿3 and R4 are independently from each other hydrogen or C1-C20alkyl or C3-C10cycloalkyl, wherein R3 and R4 are not in ortho-position to the hydroxyl group, and n is 0, 1 or 2.