CdSe nanoparticles were grown using a colloidal method, in which the pH was the main parameter that was varied (from 8 to 12) with the objective of knowing the morphological and structural effects after the synthesis process. The samples were characterized with X-ray diffraction and High-Resolution Transmission Electron Microscope to know their crystalline structure. We identified the formation of two crystalline phases in a single sample, as well as the different crystal direction of the material, the crystallites size was calculated from the X-ray diffraction pattern using the Debye- Scherrer equation. The distance between planes was also calculated using the Fast Fourier Transformation (FFT). The results and analysis of the experimental work are reported.