Homa Bay Senator Otieno Kajwang' died Tuesday night after suffering cardiac arrest.
Mr Kajwang’ died at 11.34pm at Mater Hospital in Nairobi where he was rushed after complaining of chest pains.
Tom Joseph Kajwang’, who is also the Ruaraka MP, said his brother was rushed to the hospital at 9.30 pm on Tuesday.
The body of the late senator has been moved from Mater Hospital to Lee Funeral Home.
Speaking at Mater Hospital shortly after midnight, Senate Majority Leader Kithure Kindiki said the country has lost a great leader.
Orange Democratic Movement (ODM) spokesperson Philip Etale had confirmed the death shortly after midnight.
"Sad to have lost Senator Otieno Kajwang'. It is by the will of God that Senator had to depart from our midst at this time," he said in a post on his Facebook page.
Elgeyo-Marakwet Senator Kipchumba Murkomen said on Twitter that he was shocked by the death of the ODM senator.
"So shocked that my colleague and friend Senator Kajwang' has passed on .Will remember him as passionate and eloquent debater. A man full of life and humour," Murkomen tweeted.
According to the American Heart Association, cardiac arrest is the abrupt loss of heart function in a person who may or may not have diagnosed heart disease. The time and mode of death are unexpected. It occurs instantly or shortly after symptoms appear.