In a process for purifying graphene nanoribbons, a composition comprising graphene nanoribbons GNR1 and at least one contaminant is brought into contact with a liquid medium that includes a dispersant. The graphene nanoribbons GNR1 are dispersed in the liquid medium so as to obtain a liquid dispersion of the graphene nanoribbons GNR1. The liquid dispersion of the graphene nanoribbons GNR1 is subjected to a separation treatment so as to at least partly remove the at least one contaminant, thereby obtaining a liquid dispersion of purified graphene nanoribbons GNR1.