This work is devoted to microwave heating of graphite, sucrose, calcined sucrose, and a mixture of graphite with sucrose to produce carbon nanotubes (CNT's). The samples were submitted to microwave radiation (power 800W, frequency 2.45 GHz) in air and high vacuum (10−5Torr) for 30 – 60 min. The oven temperature was approximately 1200°C. After vaporization the condensed material was collected on various fused silica targets (different morphologies were used). The samples were found to contain a significant proportion of nanotubes, nanoparticles and fibers (1-2.8 micrometers), which appeared to be highly graphitized and helical structured. After deposition, the morphology of carbon nanotubes was studied with SEM, TEM and AFM techniques. It was observed that multi-walled nanotubes (MWNT's) were produced by this method. The morphology of fused silicon based substrates (SiO2, SiC) was studied as an important factor for the growth of carbon nanotubes. Many aspects as the size and shape of the obtained nanotubes on different substrates (porous and non-porous fused silicon substrates) were achieved, as well as the concentration of them across the substrate and other properties.