The present work uses Co catalyst with CaCO3 substrate for CNTs synthesis. The Co catalyst prepared with 1%, 3%, and 5% weight percentage. The CNTs synthesis is carried out from 600 to 750°C. It is observed that for 1% catalyst loading, purified CNTs obtained at 750°C is 0.8887 grams. The similar trends obtained for 3% and 5% catalyst weight percentage. Scanning Electron Microscope (SEM) images show large bundles of CNTs with the average diameter of 29.31nm. The CNTs production models are developed. It is observed that models developed are closely related to the experimental results with the error band of 14.28%.