During hot deformation of an AA1200 type alloy significant deformation stimulated static precipitation of Fe and Si was observed for deformation temperatures lower than 330 C. It was shown to be possible to monitor Si in solid solution separately from solute Fe by combining TEP and resistivity measurements at room temperature. This revealed different precipitation kinetics for Fe and Si during hot deformation. Subsequent TEP and resistivity measurements during isothermal ageing, supported by thermodynamic calculations, showed that for long ageing times at low temperatures less alpha-AlFeSi had formed compared with thermodynamic equilibrium and that a non-equilibrium amount of Si was retained in solid solution. Furthermore a large decrease in solute Fe during annealing of cold rolled material was seen to coincide with recrystallisation.