University bosses enjoyed salary packages worth more than £250,000 on average last year, with some handed pay hikes of over 10%, it has been revealed.
Vice-chancellors also ran up bills worth thousands of pounds for hotels, flights - often travelling in first or business class - and other expenses, figures show.
The University and College Union (UCU), which obtained the data through freedom of information requests, said staff and students would be "amazed" at the size of university leaders' salaries and the "largesse" displayed by some in expenses.
The findings come at a time when vice-chancellors' salaries are increasingly under the spotlight.
Last year, ministers publicly criticised spiralling pay, saying they had serious concerns about the ''substantial upward drift'' of salaries, and that university leaders should show ''much greater restraint''.
UK universities are independent institutions but they receive public grants, and students receive government loans to pay tuition fees.
UCU asked 155 UK universities and colleges a series of questions about vice-chancellors' pay packages, including benefits and pensions, as well as money spent on air fares, hotel accommodation and personal expenses, for the year ending July 31 last year.
Around 16% - 24 institutions - did not respond or cited exemptions and did not release the requested information.
The findings show that the average overall salary package for university heads in 2013/14 was £260,290. This is based on data from 150 institutions.
A total of 18 vice-chancellors saw their pay rise by more than 10%, UCU calculated.
The top earner was Professor Neil Gorman, of Nottingham Trent University, who retired last year. His pay packet including benefits and pension for 2013/14 was £623,000, UCU's figures show, up 70.2% on the year before.
The average expenditure on flights for university leaders, with information from 128 universities, was £9,705.75. The most was spent by the London School of Economics and Political Science (LSE), which paid out £59,811.14 on flights for director Professor Craig Calhoun.
Overall just over two-thirds (67.6%) of air fares were for first or business class, UCU said, according to data from 114 universities.
The average spend on hotel accommodation during 2013/14 was £3,202.05, based on data from 122 institutions. The most was spent by Glasgow Caledonian University for Professor Pamela Gillies at £27,271.13.
The average received by vice-chancellors in personal expenses was £3,112.61, according to information gathered from 125 universities. The highest amount - £33,526 - was given to Professor Gavin Henderson of the Royal Central School of Speech and Drama.
UCU general secretary Sally Hunt said: 'Many staff and students will be amazed at the size of vice-chancellors' salaries, and at the largesse displayed by some university leaders when it comes to first class flights, hotels and other expenses.
"That this is happening in public institutions which are largely funded by the taxpayer and students makes the lack of transparency and accountability surrounding senior pay and perks a national scandal."
She added that the variation in responses to the freedom of information requests was "striking".
"Too many institutions refused to provide any information on expenses and the majority showed a strong determination to keep the details of decisions on senior pay a closely guarded secret," Ms Hunt said.
Richard Bullock, chairman of Nottingham Trent University's board of governors, said: "Former vice-chancellor Professor Neil Gorman received a 2% salary pay rise in his final year as vice-chancellor.
"The additional monies reported in this year's financial accounts were paid under a scheme that was instigated in 2008 to operate over a five-year period. This scheme was put in place by the board following independent, external advice, at a critical time in the university's strategic development which required continuity of leadership. The board were keen to retain Professor Gorman for this five-year period following a very successful initial five years."
He added that monies accrued annually were subject to meeting clear terms, with accruals declared each year.
An LSE spokesman said: "LSE is one of the most international universities in the world. Two-thirds of our students are from overseas, coming from around 145 countries worldwide, approximately 45% of our staff are from outside the UK, and we have a network of over 100,000 graduates in more than 190 countries. In addition to a range of international exchanges and connections, LSE has formal academic partnerships with universities in New York, Paris, Singapore, Cape Town and Beijing.
"A key part of the director's role at LSE is to maintain the array of international relationships and establish new links with universities, businesses and non-governmental organisations around the world. Inevitably this involves a significant amount of international travel. None of this travel is in first class."
A Glasgow Caledonian spokeswoman said: "Universities operate in a fiercely competitive global sector and GCU's ambitious international strategy reflects this, with the principal and vice-chancellor having the lead role in relationship-building for flagship developments and for graduation ceremonies.
"GCU is the first Scottish university to open a campus in London and it established the UK's first campus in New York in 2013/14, with further key partnerships in Bangladesh, Oman and South Africa.
"This has inevitably required extended trips to our overseas locations and having increased costs. The university is transparent about expenses incurred."