Figures released by the Insolvency Journal show three companies a day were declared insolvent last month as 112 companies were forced to close.
The number of businesses failing this year is 25% higher than in 2009.
However May's figures show the rate of corporate failure is slowing down, with the numbers of companies closing declining for the third consecutive month.
The compilers, InsolvencyJournal.ie, say a similar dip in figures was also recorded this time last year, when company failures dropped in both April and May before increasing significantly in the second half of the year.
Dublin continues to account for the majority of failures with 263 insolvencies in the year-to-date - 40% of all insolvencies. Construction accounted for 28 of the 112 insolvencies in May.
'At this stage it is too early to tell whether the decline in failures indicates an improvement in the economy or just another seasonal dip in figures, said Ken Fennell, partner with Kavanagh Fennell.
