The 33S(n,a)30Si cross section measurement, using 10B(n,a) as reference, at the n_TOF Experimental Area 2 (EAR2) facility at CERN is presented. Data from 0.01¿eV to 100¿keV are provided and, for the first time, the cross section is measured in the range from 0.01¿eV to 10¿keV. These data may be used for a future evaluation of the cross section because present evaluations exhibit large discrepancies. The 33S(n,a)30Si reaction is of interest in medical physics because of its possible use as a cooperative target to boron in Neutron Capture Therapy (NCT).