Rehn is scheduled to meet President Stjepan Mesic, Prime Minister Ivo Sanader, and other representatives of Croatian authorities.
The EU decided to open membership talks with Croatia on Monday.
The EU is ready for rigorous and fair talks with Croatia and Turkey. The process of screening will start on 20 October for both countries, Rehn told a news conference on Tuesday afternoon, several hours after accession talks with the two countries were opened.
On Saturday evening Rehn and Croatian officials are expected to attend a World Cup 2006 qualifying match between the Croatian and Swedish football teams.