Low temperature phase transition properties of ammonia borane (AB) and its composites with polyacrylamide (PAM) were studied by using FTIR and DSC techniques between 160 and 300 K. AB undergoes phase transition from tetragonal to orthorhombic at around 223 K via heat capacity measurements. Transition enthalpy and entropy values were determined for AB and ammonia borane/polyacrylamide (ABPAM) composites. A decrease from 24.6.1/g to 7.9.1/g was detected for the enthalpy of the transition which is due to the decreasing amount of AB in the composites. We didn't see any difference in the phase transition temperature for different composites of AB from DSC study however, some differences were detected in variable temperature transmittance measurements. Phase transition is evident from the splitting and shifting of the vibrational modes. For pure AB, splitting is more evident when compared to ABPAM composites. The stretching frequency for proton donor -NH3 and proton acceptor -BH3 didn't show any change above 223 K. Below the transition temperature, individual doublet peak from singlet showed moderate shift with corresponding decrease in temperature for -NH3 (pure AB). That splitting wasn't observed for the polymer composites which indicates phase transition of AB is affected in -NH3 moiety after the addition of PAM. (C) 2018 Elsevier B.V. All rights reserved.