Inflation in the eurozone was down to 0.5% in May 2014, dropping from 0.7% in April.
A year earlier inflation stood at 1.4%.
The rate in May for Portugal was -0.3%. May was the fourth month in a row of negative rates.
Last April, Portugal’s rate was 0.9%.
Portugal is one of three eurozone countries in deflation with negative annual rates. It joined Greece (-2.1%) and Cyprus (-0.1%).
The highest annual increases were recorded in Austria (1.5%) and Luxembourg (1.4%).
The euro region as a whole saw prices fall for fruit, vegetables and telecommunications while prices rose slightly for tobacco, electricity, restaurants and cafés.
