Mechanical losses spectroscopy of two superconducting Y1Ba2Cu3O7-x samples (T-c = 93 K) measured at 5, 10, 20 and 30 MHz revealed four peaks. As the frequency of measurement was increased, the peaks shifted to higher temperatures. The relaxation process was found to have an activation enthalpy of 0.188, 0.092, 0.209 and 0.314 eV with an attempt frequency, f(o), equal to 2.46 x 10(15), 5.95 x 10(10), 1.64 x 10(14), and 7.82 x 10(13) Hz for P-1, P-2, P-3 and P-4 peaks, respectively. The mechanism responsible for these relaxation peaks is discussed. The infrared spectra of some of these compounds provide evidence for oxygen rearrangement on going from tetragonal to orthorhombic phase. X-ray diffraction analysis shows that these compounds correspond to a single phase which is an orthorhombic perovskite structure.