Composition for cooling a propulsion system of an electric or hybrid vehicle including at least one battery, comprising (i) at least one base oil, or at least one hydrocarbon-based fluid with a boiling point of greater than or equal to 50°C; (ii) at least one fire retardant corresponding to formula R F -L-R H in which R F is a perfluorinated or partially fluorinated group, in particular including from 1 to 22, preferably from 1 to 20 and even more preferentially from 1 to 16, carbon atoms, R H is a hydrocarbon-based group, in particular including from 1 to 22, preferably from 1 to 20 and even more preferentially from 1 to 16, carbon atoms, and L is a linker, in particular chosen from the following divalent groups: -CH 2 -, -CH=CH-, -O-, -S- or -PO 4 -; and (iii) at least one fluoro compound with a boiling point of between 50°C and 250°C, different from the fire retardant of formula, the mass ratio of the fire retardant corresponding to formula /fluoro compound with a boiling point of between 50°C and 250°C being between 0.2 and 200, preferably between 0.5 and 50, said base oil or said hydrocarbon-based fluid with a boiling point of greater than or equal to 50°C being present in the composition in a content of greater than or equal to 80% by weight, relative to the total weight of the composition, and said fire retardant of formula being present in a content of greater than or equal to 0.5% by weight, relative to the total weight of the composition. (i) at least one base oil, or at least one hydrocarbon-based fluid with a boiling point of greater than or equal to 50°C; (ii) at least one fire retardant corresponding to formula R F -L-R H in which R F is a perfluorinated or partially fluorinated group, in particular including from 1 to 22, preferably from 1 to 20 and even more preferentially from 1 to 16, carbon atoms, R H is a hydrocarbon-based group, in particular including from 1 to 22, preferably from 1 to 20 and even more preferentially from 1 to 16, carbon atoms, and L is a linker, in particular chosen from the following divalent groups: -CH 2 -, -CH=CH-, -O-, -S- or -PO 4 -; and R F is a perfluorinated or partially fluorinated group, in particular including from 1 to 22, preferably from 1 to 20 and even more preferentially from 1 to 16, carbon atoms, R H is a hydrocarbon-based group, in particular including from 1 to 22, preferably from 1 to 20 and even more preferentially from 1 to 16, carbon atoms, and L is a linker, in particular chosen from the following divalent groups: -CH 2 -, -CH=CH-, -O-, -S- or -PO 4 -; and (iii) at least one fluoro compound with a boiling point of between 50°C and 250°C, different from the fire retardant of formula, the mass ratio of the fire retardant corresponding to formula /fluoro compound with a boiling point of between 50°C and 250°C being between 0.2 and 200, preferably between 0.5 and 50, said base oil or said hydrocarbon-based fluid with a boiling point of greater than or equal to 50°C being present in the composition in a content of greater than or equal to 80% by weight, relative to the total weight of the composition, and said fire retardant of formula being present in a content of greater than or equal to 0.5% by weight, relative to the total weight of the composition. the mass ratio of the fire retardant corresponding to formula /fluoro compound with a boiling point of between 50°C and 250°C being between 0.2 and 200, preferably between 0.5 and 50, said base oil or said hydrocarbon-based fluid with a boiling point of greater than or equal to 50°C being present in the composition in a content of greater than or equal to 80% by weight, relative to the total weight of the composition, and said fire retardant of formula being present in a content of greater than or equal to 0.5% by weight, relative to the total weight of the composition.