After completing his studies in France, he was an administrator at the "Office de Radiodiffusion Télévision Française" from November 1964 to June 1967. He then returned to Togo and was appointed by President Gnassingbé Eyadéma as Secretary-General of the Ministry of Finance in July 1967. Kodjo participated in the creation of the Rally of the Togolese People (RPT) ruling party in late 1969 and became the new party's Secretary-General. He also wrote the "Green Book", which served as the ideological basis for the establishment of the RPT's single-party rule. He was removed from his position as RPT Secretary-General in 1971.