On 28 July 2008 he signed a five-year contract with Empoli, using the Webster ruling to leave Wisla. Wisla brought the matter to FIFA but in October the organization cleared Kokoszka to play for Empoli. He debuted for his new club in a 4-0 win over U.S. Sassuolo Calcio on 28 October.
Although he had made only a few appearances for his club, he was noticed by Leo Beenhakker and debuted for the Poland national football team a short while later, in a friendly away to the United Arab Emirates on 6 December 2006. In the next friendly match against Estonia he scored his first goal for Poland. He was called up for Euro 2008 and made one appearance, in Poland's final match against Croatia.