On Thursday, Leko will meet with representatives of the Croat community in Germany, while on Friday will he attend the ratification at the Bundesrat.
He will also meet with Bundestag Speaker Norbert Lammert and Bundesrat Speaker Winfred Kretschmann.
Germany is the last EU member to ratify Croatia's accession treaty. Croatia joins the Union on July 1 as its 28th member country.