The influence of aluminium or niobium doping on the thermoluminescence (TL) of polycrystalline tetravalent tin dioxide is studied. The non-stoichiometry of SnO_2−x is characterised by the presence of oxygen vacancies. These vacancies, once or twice ionised behave as donor centres. Introduction of trivalent or pentavalent impurities in the matrix constitute an efficient way to control the native defects of SnO₂. Thus, tin oxide samples are doped with aluminium(III) or niobium(V) by impregnation technique. Hydroxyl groups OH are also supposed to play an important role in the TL of the oxide The deconvolution of SnO₂ TL curve is carried out in order to identify the trap parameters of the defects Besides, a quasi-chemical model is developed. This theoretical approach allows to foresee the behaviour of points defects versus dopant species concentration. Correlations with experience lead to the identification of these point defects.