Returning to Congo in 1965, he was a history professor at the École normale supérieure d'Afrique Centrale in Brazzaville from 1965 to 1966, then Director-General of Education from 1966 to 1968.

[9] After working as political director of the party newspaper Etumba from 1975 to 1977,[10][7] Lopes was reappointed to the government as minister of finance on 5 April 1977;[11] he served in that position until Justin Lekoundzou was appointed to replace him in December 1980.

[7] In 2002, Lopes was a candidate for the post of Secretary-General of the international organization La Francophonie, but he withdrew his candidacy under pressure on the night before the vote, which was held on 20 October 2002 and resulted in the unanimous election of Senegal's Abdou Diouf.

[19] During the conference Lopes received the award of Honorary Membership of PAWA, alongside other honorees who included the late Kwame Nkrumah, Emeritus Professor Ekwueme Michael Thelwell, Dr Margaret Busby, James Currey, Professor Jophus Anamuah-Mensah, Dr Joyce Rosalind Aryee and others.

[20] Lopes also wrote the words to "Les Trois Glorieuses", which served as the national anthem of the People's Republic of the Congo from 1970 to 1991.