Differential scanning calorimetry (DSC) has been used to simulate laser fusion of ceramic precursors to prepare BSCCO high temperature superconducting materials. At fast heating rates, typical of the laser floating zone, the energy required for complete melting of the precursor increases with the Bi to Sr + Ca ratio, in agreement with the critical current results obtained. At low heating rates, solid-state reactions involving ionic rearrangements take place before incongruent melting. These changes can be divided into three processes and can be quantified from calorimetric measurements. Lower heating rates and isothermal experiments allow detailed visualisation of the ionic arrangements taking place. The results prove that the mechanism of the final phase formation is dependent on the fabrication procedure. (C) 2003 Elsevier B.V. All rights reserved.