"It is with deep sorrow and shock that we announce the sudden passing on of Interior CS Retired General Joseph Nkaissery," Joseph Kinyua, the chief of staff and head of the public service, said in a statement.
"Gen. Nkaissery passed on at Karen Hospital in Nairobi a few hours after being admitted for a check-up," he said.
No further details were released.
Kenyans will choose their next president, legislators and local representatives on Aug. 8.
President Uhuru Kenyatta is running against his long-time rival, veteran opposition leader Raila Odinga.
But 2013 polls passed relatively peacefully after Odinga challenged the results in court.
Nkaissery's death is unlikely to affect preparations for the elections.
(Reporting by Katharine Houreld; Editing by Robert Birsel)
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