The man appointed by the Holy Ghost to go on the missionary journey with Saul was
Answer Details
The man appointed by the Holy Ghost to go on the missionary journey with Saul was Barnabas. After Saul's conversion, he became a preacher of the gospel and started preaching boldly in Damascus. When the disciples in Jerusalem heard about this, they were afraid of him and did not believe he was a disciple. However, Barnabas took Saul under his wing and introduced him to the other apostles. Later, the Holy Ghost spoke to the prophets and teachers in the church at Antioch, telling them to separate Barnabas and Saul for the work to which He had called them. Therefore, the answer is Barnabas.