When the House of Commons Justice Committee called for evidence on the effectiveness of the FoI Act, 23 universities submitted evidence, of which 18 complained about the cost burden, among other concerns.
But Jisc, the UK's expert body on information and digital technology in higher education, tracked 36 requests in seven institutions and found that the average cost, including staff time, of answering an FoI request was £121.
According to Universities UK, higher education institutions received on average 10.1 requests a month in 2011. This equates to an average annual cost of £14,665, which across the sector's 155 institutions adds up to £2.3 million a year.
Steve Bailey, a senior adviser at Jisc infoNet who oversaw the research, explained that this was not the only way to count the cost of FoI legislation, as institutions still spent roughly £7.2 million a year on employing FoI officers.
There would be some "double counting" between the two calculations because FoI officers did some of the enquiry processing, but neither calculation included legal fees, he said.
If the two estimates are added together, the resulting figure of £9.5 million would be roughly a third of the total spent on vice-chancellors' pay and benefits, based on average figures for 2009-10.
Nicola Dandridge, chief executive of Universities UK, said the research showed that the costs of complying with the Act were "considerable".
In its submission to the Justice Committee, Nottingham Trent University said that some enquiries were submitted "purely to cause irritation" while others engaged in "speculative muck-raking" in the hope of achieving a "journalistic scoop".
This caused a "substantial drain on the organisation's resources for no good purpose", it said.
Mr Bailey said that universities needed to be able to make their record systems easy to access.
Universities could also consider whether they might save money by delegating some enquiry processing to a lower grade of staff, he added.