Abstract The specific heat of two LATGS single crystals of different habits, grown from solutions of TGS containing different proportions of L-alanine, has been studied. The measurements were made between 303 K. and 328 K by decreasing and increasing the temperature at various constant rates ranging from 0 to 0.6 K/h, The specific heat depends on decreasing temperature rate. Relaxation processes with a time constant of 14 h have been also observed. This behaviour is qualitatively explained by assuming that viscoelastic effects are involved in the mechanical process which orients and stabilizes the direction of glycine I, as a consequence of the deformation of the unit cell when L-alanine is introduced.