Up to now all ceramics of REBa2Cu3O7-delta (RE = Y and rare-earth elements) were prepared at temperatures of about 900-950 degrees C except Lu123. LuBa2Cu3O7-delta could not be prepared as single-phase ceramic. In the present study, we have developed the preparation conditions to synthesize phase-pure Lu123 ceramics. We have measured the resistivity of Lu123 (T-c = 92.1 K) at different temperatures, determined the enthalpies of reaction including LuBa2Cu3O7-delta by solution calorimetry and have studied the thermodynamic stability of this compound. (C) 2007 Elsevier B.V. All rights reserved.