Somali President Hassan Sheikh Mohamud has reached Sudanese city Umdurman to participate in the swearing ceremony of President Omar Hassan Al Bashir.
Al-Bashir extended his quarter-century in power with landslide election victories for 94.4 percent during last month general elections.
Several African and Arab leaders are expected to attend the ceremony near the capital..
Leaders from Djibouti, Egypt, Kenya, Zimbabwe and Chad are among others from the region.
Bashir took over power in a bloodless coup in 1989.
Sudan is among Muslim countries that have reestablished their diplomatic ties with Somali government.