The present invention relates more specifically to a cosmetic treatment method intended in particular to improve the appearance of the skin and/or hair comprising the simultaneous and/or sequential administration: a) of at least one cytochrome C oxidase substrate and/or of at least one agent which increases the expression of the said substrate; and b) of at least one light radiation exhibiting at least one predominant wavelength which activates cytochrome C oxidase. In particular, the said light radiation exhibits at least one predominant wavelength which activates cytochrome C oxidase ranging from 550 to 1000 nm, in particular from 550 to 800 nm, preferably from 620 to 700 nm and more preferably still from 640 to 680 nm and is preferably used at a dose ranging from 0.01 to 200 J/cm2, preferably from 0.1 to 30 J/cm2, more preferably from 1 to 30 J/cm2, indeed even from 5 to 30 J/cm2.The invention also relates to a composition comprising at least one cytochrome C oxidase substrate and/or one agent which increases the expression of the said substrate and at least one compound emitting and/or filtering, in particular under exposure to light, a light radiation exhibiting at least one predominant wavelength which activates cytochrome C oxidase, and to a kit comprising at least one composition comprising at least one cytochrome C oxidase substrate and/or one agent which increases the expression of the said substrate and one device and/or one compound emitting/filtering a light radiation exhibiting at least one predominant wavelength which activates cytochrome C oxidase.