Bonchari residents are on Tuesday voting to decide who will represent them in the National Assembly.
Polls opened at 6am and will remain open until 5pm
Bonchari Returning officer Benson Ambuko said there are two officers manning each polling station but the number can be increased if voters are many and depending on circumstances.
"The Interior Ministry has ensured enough security and we call on voters to come out in large numbers and vote," said Mr Ambuko.
A total of 13 candidates are on the ballot. The seat fell vacant after the death of Oroo Oyioka.
The constituency has 52, 955 voters and 03 polling stations.
Mr Zebedeo Opore is flying the Jubilee party ticket while Ms Teresa Bitutu who is the widow to the former Bonchari MP , Mr Oyioka, is the United Democratic Alliance(UDA) flag bearer in the by-election.
Pavel Oimeke is the ODM candidate. Former Kisii Woman Rep Mary Sally Keraa (United Green Movement), Jonah Onkendi Ondieki of The New Democrats (TND), Charles Mogaka Ndege of Progressive Party of Kenya (PPK), David Ogega Oyugi (Kenya Social Congress) and Margaret Gesare Nyabuto (Maendeleo Chap Chap) are among the 13 candidates.
Mr Kevin Mosomi of the Party of Democracy Unity (PDU), Jeremiah Atancha of Agano party, Victor Omanwa (Party of Economic Democracy), Nyakea Erick Oigo (National Reconstruction Alliance) and Paul Matagaro (Mwangaza Tu Party) are also vying in the mini poll.