The delta' precipitation process was studied by isothermal Thermoelectric Power (TEP) and non-isothermal Differential Scanning Calorimetry (DSC) measurements in the Metal Matrix Composite 8090 Al-Li/SiC and the alloy 8090 Al-Li. The kinetics obtained by TEP at different ageing times were analysed following the Johnson-Mehl-Avrami/Austin-Rickett modified model and the apparent activation energies were calculated. These energies were also obtained from DSC scans at different heating rates by the Kissinger method. It was observed that the delta' precipitation process is favoured in the Metal Matrix Composite. This acceleration could be related to the presence of gradients of thermal stress within the matrix.