The Independent Electoral and Boundaries Commission (IEBC) has received 192 pallets of presidential ballot papers.
The electoral commission received the consignment, to be used in the August 8, General Election, at the Jomo Kenyatta International Airport (JKIA) on Monday evening.
In total, there are 353 pallets and the first batch of 192 for 30 counties arrived at the JKIA in Nairobi from Dubai on Monday.
According to the IEBC, the rest - 161 pallets - will be delivered on Tuesday.
After all the ballot papers are delivered, they will be cleared and taken to the commission's warehouses for distribution to the counties.
But concerns have been raised about an extra 1.2 million presidential ballots that have been printed by Dubai-based firm Al Ghurair Printing and Publishing LLC.
The IEBC is allowed to print extra ballots, but only one per cent of the total registered voters, who according to official figures are, 19,611,423, which means that the electoral agency should have an excess of only 196,115.
The agency has said there are 20,818,000 printed presidential ballot papers, including the one per cent provision in case of spoilt votes, which exceeds the constitutionally allowed threshold.
IEBC has further explained that there are more papers than the number of voters because each booklet has 50 sheets.
Commissioner Roselyn Akombe said the IEBC had rounded off the extra requirement in each polling station to the nearest 50 and explained it to all stakeholders.
The agency has also mapped out 40,883 polling stations that have been capped to serve not more than 700 voters each.
For instance at the Bomu Primary School polling centre, each of its 14 polling stations requires 694 presidential ballot papers, which when rounded off to the nearest 50, will be 700.
At Al-Irshadi Nursery School polling centre, 687 ballot papers for the presidential election are required for each of the seven polling stations, which also makes it 700 after rounding off.
"The one per cent additional ballot papers is meant to cater for spoilt ballots before voting. Each booklet has 50 pages," the commission says on its twitter page.
However, some presidential candidates are dissatisfied with the explanation, with Thirdway Alliance of Kenya flagbearer Ekuru Aukot saying the extra ballot are a cause of worry.
"IEBC must ensure that this particular batch of ballot papers does not mix with any other suspected fake ballot papers that can possibly be introduced in transit, especially during transport to the polling stations. "Used, un-used and spoilt ballot papers must be reconciled properly and results tallied transparently and transmitted without any hitches," he said on Sunday.
But Dr Akombe on Monday sought to allay fears that extra or foreign ballot papers would be cast irregularly.
She said presidential voting materials have been customized for each polling station and it's therefore impossible to use materials that are not specific to a station.
Dr Akombe explained that presiding officers will show party agents the number of ballot papers issued and record them in the polling day diary, complete with the unique serial numbers.
At the end of polling, the presiding officer will record the number of unused ballot papers and share the information with the agents.
IEBC will also track the number of ballots issued and compare the data with the voter turnout at that particular time every three hours.
"Any inconsistencies will be detected immediately and action taken against the presiding officers, in case of electoral offences," said Dr Akombe.
She said the 45,000 Kenya Integrated Election Management System (Kiems), whose dry run to demonstrate transmission of results was postponed on Monday, is fool-proof and cannot allow presiding officers to transmit more results than the number of registered voters in a polling station.
She said the procedure will ensure there is no ballot stuffing at any point and that the commission will annul results from any polling station that has more votes than the number of registered voters.
"This means that even in the worst case scenario of the failure of Kiems, ballot stuffing is mitigated against," the official added.
After the 2013 elections, the opposition Cord claimed that The National Alliance, then President Uhuru's party, had colluded with corrupt election officials to print extra ballot papers that were used to rig the presidential poll.
Cord leader Raila Odinga said the extra ballot papers were printed by Smith & Ouzman, a British firm, and smuggled into Kenya days before the March 2013 elections.
But the ballots to be used on Tuesday, according to Al Ghurair, have a number of security features that will make it almost impossible to manipulate.