Carbon nanotubes (CNTs) have been in recent years under studies due to its importance in the application for the preparation of new materials. One of the challenges after chemical vapor deposition (CVD) syntheses is the metallic and support removal. In this work we pressent the CNTs purification in acidic medium at various concentrations of hydrochloric acid, in order to evaluate the effects of acid on the morphology of the nanotubes and the reduction of residual metallic and support species. This study was performed using scanning electron microscopy (SEM), energy dispersive of X-ray (EDX) and thermogravimetric (TGA) techniques.