EU statistics office Eurostat said annual inflation in the 13 countries using the euro remained unchanged from April at 1.9 per cent.
The European Central Bank (ECB) wants to keep inflation below, but close to, 2 per cent. Price growth has remained at that target level since September 2006.
But markets expect the ECB to raise interest rates by a further 25 basis points to 4 per cent next week, and perhaps once more later in the year to stem medium-term inflationary pressures from a tightening labour market and fast credit growth as the economy expands at a healthy pace.
A monthly European Commission survey showed economic sentiment in the euro zone improved in May to 111.9 points, against expectations of no change from April's 111 points.
Consumer sentiment, long the weakest point of the survey, rose to minus one point from minus four in April. Economists had expected an improvement to minus three.
Inflation expectations among consumers stayed unchanged from April at 17 and rose to 12 from 11 among businesses.
The commission's business climate indicator, which points to the phase of the business cycle, eased to 1.53 for the euro zone in May from 1.61 in April. Economists polled had on average expected the May index to come in at 1.60.
The commission said the indicator remained high and pointed to strong industrial output growth in the second quarter.