Voters in Juja constituency will elect their new representative in Parliament on September 20 in a by-election.
The seat fell vacant after the High Court nullified the election of George Thuo as the area MP on a PNU ticket during the 2007 general election, in an election petition filed by former legislator William Kabogo (Sisi kwa Sisi).
Announcing the date, Interim Independent Electoral Commission (IIEC) chairman Ahmed Isaak said political parties must hand in nomination papers on August 27 and 28.
He was speaking when he issued the writs to the area returning officer Mr Benard Kimani.
Mr Thuo (PNU), who during his period in Parliament was the Joint Government Chief Whip is among six MPs who have so far lost their seats in election petitions.
Others are Joel Onyancha (Bomachoge), Omingo Magara (South Mugirango), Dick Wathika (Makadara), Chirau Ali Mwakwere (Matuga) and Abdirahman Ali Hassan (Wajir South).
Two weeks ago, Mr Mwakwere managed to recapture his seat. Mr Onyancha and Mr Magara failed to recapture their seats during the respective by-elections.
The by-elections for Makadara and Wajir South are yet to be held.