We present a study of sulfonitric treatment and its effect on MWCNTs at different temperatures (90, 110, 130 and 150ºC) using DRX, XPS, FTIR, Raman spectroscopy, TEM and zeta potential. It was found that oxidation starts with the C-C and C-H bonds generating different oxidized groups from alcohol to carboxylic acid, following a sequential oxidation. Given that heterocoagulation needs a maximum zeta potential gap between the ceramic and the MWCNT surface and it significantly exist a risk of manipulate acids at high temperature it is recommended to use acid treatment of CNT at 110 ºC for generating ceramic composites by heterocoagulation.Facultad de Ciencias ExactasCentro de Tecnología de Recursos Minerales y Cerámica