Abstract We have measured the LiF:Mg,Ti (TLD-100) thermoluminescent response, efficiency and supralinearity, to 3 and 7.5 MeV helium ions in the fluence interval between 6×10 7 to 1.5×10 11 cm −2. Ion irradiations were performed using a flux of elastically scattered ions from a thin gold target. The measured efficiencies with respect to 60Co γ-rays are equal to 0.074 and 0.174 at 3 and 7.5 MeV, respectively, for the response of peak 5. The supralinearity functions for peaks 4, 5, 6a, 6b, 7, 8, 9 and the total TL signal indicate that supralinearity is an increasing function of energy and that it increases with peak temperature. The data for peaks 5, 8 and 9 have been successfully described by Monte Carlo simulations of the track interaction model. The fitted parameters show that peak 5 displays a special behaviour which requires the use of a much larger effective track radius than the higher temperature peaks.