Most of the supporting catalytic materials seek to improve classical chemical processes that are less environment-friendly. The association of heteropolyacids (HPA) and zeolites has shown to be interesting for heterogeneous catalysis. In the present study, zeolite Y (faujasite) was modified by the incipient insertion of 12-tungstophosphoric (HPW) and 12-tungstosilicic (HSiW) acids for application in the esterification reaction of oleic acid with n-butanol. The fine chemical product (butyl oleate) is used in a variety of applications (e.g., plasticizers, lubricants). The catalysts (x%HPA/Y; x = 3, 6 and 12%) were characterized by EDXRF, XRD, FT-IR, multinuclear MAS NMR (27Al, 29Si, and 31P), SEM, low temperature N2 physisorption, thermal methods (TG/DTG), pyridine (Py) gas desorption (Py-TPD) and microcalorimetry of Py adsorption in liquid phase. The resulting acid composites showed advantages over both pristine solids with adequate nature, dispersion, stability, accessibility, and strength of active sites. High oleic acid conversions (70% for 12%HSiW/Y and 96% for 12%HPW/Y) with 100% selectivity to butyl oleate were obtained under these conditions: acid: alcohol ratio 1:2; 0.2 g of catalyst; 100°C and 1 h reaction. No leaching of the active phases was detected, and the best catalysts were used three times, keeping fair their initial conversion.