Abstract Uniform colloidal monodispersed silica nanoparticles were synthesized via stöber method using ammonia as a basic catalyst. Field Emission Scanning Electron Microscope (FESEM) was confirmed the homogeneous nanospheres. The decrease of TEOS concentration (0.067 to 0.012 mol L-1) and an increase of H2O concentration (3 to 14 mol L-1) at 14 mol L-1 NH3 fixed accelerated the rate of hydrolysis and condensation of [Si (OC2H5)4-X(OH)X]. Using EtOH solvent prevented the aggregation of micelle nuclei and formed spheres with the smallest variance in their size. Hence, the spherical particles were tuned in the range of 10-330 nm. Moreover, the decrement of the ultrasonic time could be changed the nanospheres morphology to the mesoporous structure.