Abdullah arrives in Berlin from Italy, where he was received at the Vatican by Pope Benedict XVI in the first ever meeting between a pontiff and reigning Saudi king, the protector of Islam's holiest sites.
Merkel is to receive Abdullah with military honors at the chancellery Wednesday, then hold talks with him that her spokesman, Ulrich Wilhelm, has said are to focus on developments in the Middle East. No news conference is planned.
Merkel met Abdullah in Riyadh during a tour of the region in February.
On Wednesday evening, the king also is to meet German President Horst Koehler.
The king's visit is part of a European tour that already has taken him to Britain, where he discussed terrorism and the Middle East peace process with Prime Minister Gordon Brown.