The influence of the cadmium and the indium on the kinetics of the delta' metastable phase precipitation has been studied in Al-8.5at.%Li and Al-8.5%at.%Li0.2at.%In(0.3%at.%Cd) solid solutions. From the hardness isotherms the volumic fraction of the formed delta' metastable phase is determined for different times of ageing at 150, 180 and 200 degrees C. The incubation times of delta' deduced from the precipitation kinetics show that In and Cd atoms retard the delta' precipitation.