A former president of the national assembly and member of the former ruling party – the Front Populaire Ivoirien (FPI) – Koulibaly stood back from ex-president Laurent Gbagbo during the 2011 post-election crisis.
Largely seen as a moderate, he was one of a few heavyweights not being arrested following the crisis.
In April 2011 Koulibaly became acting president of the FPI.
He resigned three months later, saying he was frustrated by the inability of the hardliners to move on.
He now has his own party, Liberté et Démocratie pour la République, which aims to stand as a "strong opposition" to President Alassane Ouattara's "absolute presidentialist power".