He took part in the inaugural World Championships in Athletics, and was knocked out in the quarter-final stage of the men's 400 m. In 1984 he started by winning the 400 metres event at the African Championships in Athletics in Rabat. A few weeks later, at the Olympic Games, he managed to win the silver medal with 44.54 seconds, a new African record. At 20 years of age, Tiacoh had become the first Olympic medal winner from a West African country. He also ran in the 4×400 metres relay at the competition, but the men's team (including Georges Kablan Degnan, Avognan Nogboum and René Djédjémel Mélédjé) was knocked out in the semi-finals.