The temperature dependence of NQR parameters and proton spin-lattice relaxation times of furosemide in forms 1 and 2 are reported. The NQR line shape shows that form 2 is disordered, even at low temperatures and reorientation of the SO2NH2 group between conformers has been detected above 120 K. Through T-1H measurements a transition of form 2 to the high temperature phase of furosemide is observed around 405 K. The high temperature phase is characterized by one NQR line indicating Z' = 1 in this phase. Proton transfer and NH2 jumps in form 1 are also observed through T-1Q. measurements. (C) 2015 Elsevier B.V. All rights reserved.