Two police officers have been assigned to each polling station.
So, far no incidences have been reported during the exercise.
Machakos County IEBC returning officer Joyce Wamalwa while addressing reporters at Kathome polling station in Machakos Constituency said names of all the 11 candidates cleared for the Machakos senatorial by-election are on the ballot.
Candidates Agnes Kavindu (Wiper) is expected to cast her vote at Kathome shopping centre polling station in Machakos Constituency.
Alburnas Ngengele of UDA is expected to cast his vote at Mwala Primary School in Mwala Constituency.
Maendeleo Chap Chap Party Leader and Machakos Governor Alfred Mutua will cast his vote at Mathatani primary School in Mavoko Constituency.
Transport CAS Wavinya Ndeti is expected to cast her vote at Makadara Resource Centre in Mavoko Constituency.