The present work illustrates the synthesis of 4-sulfophenyl activated carbon based solid acid catalyst (ACPhSO(3)H), obtained from activated carbon (AC) by arylation with 4-sulfobenzenediazonium chloride. The variation of reaction conditions, such as, reaction temperature (20-85 degrees C) and weight ratio of sulfanilic acid (precursor of 4-sulfobenzenediazonium chloride) to AC (0.1411-14.00/1) provided ACPhSO(3)H with relatively high density of acid sites. The ACPhSO(3)H with the highest PhSO3H density (0.72 mmol H+/g) was obtained using weight ratio of sulfanilic acid to AC (7.00/1) at 70 degrees C after 10min. The catalyst was characterized by means of nitrogen adsorption analysis (average pore diameter 10.1 nm, specific surface area 114 m(2)/g, pore volume 0.29 cm(3)/g), FT-IR, TG, XRD, FE-SEM and S elemental analysis. The spent catalyst can be easily regenerated recovering its initial density of acid sites. Upon employment in esterification reactions of rapeseed oil fatty acids, ACPhSO(3)H showed similar catalytic performance to Amberlyst-15. (C) 2015 Elsevier B.V. All rights reserved.