Abstract: This study reports the effect of the calcination processes on the structural and mid-infrared optical properties of Zn0.9 Mn0.1O nanopowders synthesized by sol-gel technique. X-ray diffraction analysis revealed that the synthesized nanopowders calcinated at low temperatures have mono-phase wurtzite structure. TEM images show that the average particle size is about 35 nm. By changing the calcination temperature, it was possible to decrease the percentage or even eliminate the presence of the secondary phases in the composition. The characterization was completed by studying the mid-infrared transmittance spectra using Fourier Transformation Infrared (FTIR) spectroscopy.