The present invention relates to a hair treatment process comprising the application to the hair of an aqueous-alcoholic composition comprising at least 5% of at least one C1-C7 alcohol and at least one organic monoacid, followed by a straightening/relaxing step using a straightening iron at a temperature of at least 100° C. The process of the invention allows good straightening of the hair, while durably reducing the volume and the frizziness effect of the hair.
