Density and sound velocity measurements and¹H NMR investigations were carried out in aqueous solution at various temperatures for determining the adiabatic compressibility (β) and hydration of the tetrapeptide, TFA. Tyr-Gly-Phe-Ala-Obz I. The present investigation showed changes in the temperature coefficient of adiabatic compressibility at 40°C,¹H NMR studies indicated the inverse temperature transition in the concentration range studied.