The maximum polling of 37.46 percent was reported from Sri Ganganagar constituency while Jhunjhunu reported the lowest of only 21.91 percent till noon.
In 2009 Lok Sabha elections, the state recorded over 48.46 percent voter turnout.
Reports of problems in EVMs came in from some districts, where the machines were repaired or changed.
Earlier in the morning, polling started amid tight vigil by security forces.
"The voting began at 7 a.m. at over 38,220 polling stations spread in these 20 constituencies. We have made elaborate security arrangements for peaceful polls," an election official here told IANS.
In all, over 80,000 security personnel have been deployed.
The political fate of 239 candidates is being decided Thursday.
Among these are Sachin Pilot, C.P. Joshi, Girja Vyas, Chandresh Kumari and Jitendra Singh of the Congress, and Sanwar Lal Jat, a minister in Vasundhara Raje government, and Olympic silver-medalist shooter Rajyavardhan Singh Rathore of the BJP, and Jaswant Singh and Buta Singh who are contesting as Independents.
The Congress and the BJP are fighting for all 20 seats, while the Aam Aami Party is contesting 17, and the Bahujan Samaj Party 18 seats.
