Analysts polled by Reuters had forecast May's CPI inflation at 4.83 percent, compared with April's 4.58 percent.
The overall consumer food price index shot up to 3.10 per cent in May, from 2.80 per cent in April, as per the Central Statistics Office (CSO).
Ruth Gregory, senior United Kingdom economist at Capital Economics said oil prices are expected to fall later this year and overall "the inflation figures have not altered our view that the [Bank of England's] MPC will probably press ahead and raise interest rates in August".
"This is 0.87 per cent points less than the 13.34 per cent recorded in April, and represents the sixteenth consecutive disinflation since January 2017".
"Despite the drop in inflation, the current inflation rate is still above the targeted single digit".
Inflation rate reduces by 0.87% from April. This was caused by the increase in price of potatoe, yam and other tubers, fish, bread and cereals, Oil and fats, vegetables, coffee, tea and cocoa, Meat, Milk, cheese and eggs.
Retail inflation now stands at a four-month high after topping the 4.58 per cent it recorded in April.
It stated the percentage change in the average composite CPI for 12 months period ended May over the average of CPI for the previous 12 months period.
The average annual rate of change of the food sub-index for the 12-month period ending May 2018 over the previous 12-month average was 18.36 per cent, 0.53 per cent points from the average annual rate of change recorded in April by 18.89 per cent.
On month-on-month basis, it stated the urban index rose by 1.10 per cent in May, up by 0.25 per cent from 0.85 per cent recorded in April.
In the same vein, the urban index rose by 1.10% in May 2018.
On month-on-month basis, it stated that inflation was highest in Adamawa (1.98 per cent), Kwara (1.79 per cent), and Kaduna (1.70 per cent), while Kogi (0.02 per cent), Lagos and Ogun (0.52 per cent each) and Cross River (0.56 per cent) recorded the slowest rise in inflation.
Air fares, which were influenced by the early timing of Easter this year, registered annual inflation of 8.2 per cent, having fallen by 7.9 per cent in the prior month.
Meanwhile, during the month under review, Kebbi State recorded the highest all-items-inflation with a figure of 14.65%.