A lot will probably depend on the country, the region of the country, the competition etc. Have you checked out other academies/schools in the area to see how much they pay? They should specify an hourly rate (or an approximate one) in any job advert.
In Madrid, TEFL teachers at an academy get anything between about €14 and €22 per hour, depending on experience, qualifications and various other factors. The size of the academy/company paying you will also make a difference. A "socio-cultural centre" sounds like a sort of council-run thing - am I right? If so, you may not get the same rate that you would get with a private academy, or if you taught privately.

English Teacher