Orange Democratic Movement leader Raila Odinga on Sunday flew out to attend the burial of former UN Secretary-General Kofi Annan in Ghana.
Mr Odinga will be away for about a week.
"Mr Odinga left the country this afternoon for a brief stop-over in the United Arab Emirates before proceeding to Ghana for Dr Annan’s burial on Thursday," his spokesperson Dennis Onyango said in a press statement.
Other senior Kenyan leaders expected at the burial is National Assembly Speaker Justin Muturi who President Uhuru Kenyatta chose as his special envoy at the burial on September 13.
The Ministry of Foreign Affairs said Mr Muturi will lead a delegation of senior members of government, legislature and an official representative from the High Commission of the Republic of Kenya in Abuja, Nigeria, which is also accredited to Ghana.
Dr Annan, 80, died on August 18 in Switzerland after a short illness.
He led the United Nations as secretary-general from 1997 to 2006.
After his retirement, he served as UN special envoy for Syria where he helped in trying to resolve the civil war that has claimed thousands of lives.
Dr Annan had won the Nobel Peace Prize for humanitarian work in 2001.
After the burial, Mr Odinga will proceed to the US to deliver a lecture at Duke University in North Carolina.
Other scheduled lecturers will be at George Washington University and Council on Foreign Relations (CFR), a non-profit think tank that specialises in U.S. foreign policy and international affairs.
The CFR lecture will take place at the organisation’s Washington, DC offices.
"While in the US, Mr Odinga is also scheduled to hold talks with government and business leaders," the statement added.