A new green synthesis route is proposed for obtaining a mesoporous material using sugarcane bagasse ash (SCBA) as the silica source. The material obtained was denoted by SBA-16 and its mesostructure was characterized by low-angle X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption techniques. Sulfonic acid groups were introduced to the as-synthesized material, resulting in an acid catalyst denoted by SBA-16/SO₃H. The catalytic activities of SBA-16 and SBA-16/SO₃H were investigated in Kabachnik–Fields reactions, where α-aminophosphonate compounds were produced. The results show that both products can be considered as promising catalysts, where SBA-16/SO₃H showed a slightly better performance than SBA-16.