The ECB Base Rate, is the interest rate set by the Governing Council of the European Central Bank (ECB) from time to time, during its monetary policy meetings. This is the basis for ECB Eurosystem Main Refinancing Operations (MRO).
The ECB Base Rate (applicable from time to time), is published on the website of the ECB. Any changes to the ECB Base Rate are publicized through a press release of the Governing Council of the ECB, regarding monetary policy decisions.
 
ECB Base Rate data available at the following address:
Key ECB interest rates (europa.eu)