Process for the optimization of a spatial distribution (Wc f x,y) of the catalyst charge (Wc) of an active layer of at least one electrode of an electrochemical cell of a fuel cell, in order to render uniform a temperature of the electrochemical cell in operation, the said electrochemical cell comprising two electrodes separated from one another by an electrolyte and positioned between two bipolar plates suitable for bringing reactive entities to the electrodes and for discharging heat produced by the electrochemical cell in operation, at least one electrode comprising an active layer comprising at least one catalyst, the active layer being suitable for generating an electrochemical reaction from one of the reactive entities, the said process comprising the following stages: i) experimental production or numerical modelling (110; 210) of an electrochemical cell within which the said catalyst charge (Wc) is distributed according to an initial spatial distribution (Wc i x,y), for which the spatial distribution of a temperature within the electrochemical cell in operation exhibits at least one local value greater than or equal to a predetermined maximum local value; ii) definition (120; 220) of a spatial distribution (T c x,y) of a set temperature (T c) within the said electrochemical cell in operation, such that the local temperature values are lower than predetermined maximum local values; iii) experimental or numerical measurement (130; 230) of a spatial distribution (D r x,y) of the effective local flow rate (D r) of a heat-exchange fluid circulating in a cooling circuit of a bipolar plate of the said electrochemical cell in operation; iv) estimation (140; 240) of a spatial distribution (Q e x,y) of the local heat flux (Q e) produced by the said electrochemical cell in operation, as a function of the said spatial distribution (T c x,y) of the set temperature (T c) and of the said measured spatial distribution (D r x,y) of the effective local flow rate (D r), so that the spatial temperature distribution of the said electrochemical cell in operation, the effective local flow rate (D r) of which exhibits the said measured spatial distribution (D r x,y) and the local heat flux (Q e) of which exhibits the said estimated spatial distribution (Q e x,y), is substantially equal to that (T c x,y) of the set temperature (T c); v) determination (150; 250) of the optimal spatial distribution (Wc f x,y) of the catalyst charge (Wc), as a function of the estimated spatial distribution (Q e x,y) of the second heat quantity (Q e). i) experimental production or numerical modelling (110; 210) of an electrochemical cell within which the said catalyst charge (Wc) is distributed according to an initial spatial distribution (Wc i x,y), for which the spatial distribution of a temperature within the electrochemical cell in operation exhibits at least one local value greater than or equal to a predetermined maximum local value; ii) definition (120; 220) of a spatial distribution (T c x,y) of a set temperature (T c) within the said electrochemical cell in operation, such that the local temperature values are lower than predetermined maximum local values; iii) experimental or numerical measurement (130; 230) of a spatial distribution (D r x,y) of the effective local flow rate (D r) of a heat-exchange fluid circulating in a cooling circuit of a bipolar plate of the said electrochemical cell in operation; iv) estimation (140; 240) of a spatial distribution (Q e x,y) of the local heat flux (Q e) produced by the said electrochemical cell in operation, as a function of the said spatial distribution (T c x,y) of the set temperature (T c) and of the said measured spatial distribution (D r x,y) of the effective local flow rate (D r), so that the spatial temperature distribution of the said electrochemical cell in operation, the effective local flow rate (D r) of which exhibits the said measured spatial distribution (D r x,y) and the local heat flux (Q e) of which exhibits the said estimated spatial distribution (Q e x,y), is substantially equal to that (T c x,y) of the set temperature (T c); v) determination (150; 250) of the optimal spatial distribution (Wc f x,y) of the catalyst charge (Wc), as a function of the estimated spatial distribution (Q e x,y) of the second heat quantity (Q e).