Chelsea Football Club and FC Cologne have agreed a season-long loan for Tomas Kalas which will begin on 1 July.
The Czech defender, 21, will embark upon his second loan spell away from Stamford Bridge having previously spent two seasons – 2011/12 and 2012/13 – at Vitesse Arnhem.
He returned to Chelsea ahead of the 2013/14 campaign and was handed his debut by Jose Mourinho as a late substitute in a 2-0 Capital Cup win at Arsenal.
He then made his European bow for the club, again as a late sub, in our 2-0 Champions League Round of 16 win over Galatasaray at Stamford Bridge.
The youngster was handed his first start in our 2-0 Premier League win at Liverpool in April, playing alongside Branislav Ivanovic at the heart of the defence and impressing with a composed, mature display.
On the final day of the season he made his second start in our 2-1 win at Cardiff City. Though generally considered a central defender, Kalas, who has one senior international cap, also played at right-back while with Vitesse.
Cologne were promoted back to the German top flight at the end of last season, ending the campaign as second division champions, six points ahead of second-placed SC Paderborn 07.
They are managed by former Austrian international Peter Stoger.