Abstarct: In this work, magnesium ferrite powders (MgFe2O4) were firstly synthesized by the sol-gel auto-combustion and microwave methods. Synthesized sol-gel auto-combustion samples were annealed at 500 oC (S-G500), 600 oC (S-G600) and 700 oC (S-G700). Synthesized microwave sample was also annealed at 600 oC (MW600). In order to investigate the sensing properties of the samples, some disks with radius of 15 mm were made by the prepared powders. Then, the structural and optical properties of the samples were investigated. Structural and optical parameters of the samples were measured by the X-Ray diffraction analysis, scanning electron microscope (SEM) and UV-Vis spectroscopy respectively. X-ray diffraction patterns indicated that all samples have cubic spinel crystal phase of magnesium ferrite wihtout any impurity phase. It was also seen as the calcination temperature increases, the crystallite size also increases. The results also showed that synthesized microwave sample (MW600) have smallest crystallite size. SEM images of the samples showed that the surface of all samples are including nearly spherical particles with uniform distribution. It was also observed MW600 sample have more porosity than S-G600 sample. UV-Vis Spectroscopy analysis indicated as the calcination temperature increases, the adsorption of the samples increases and the band gap energy decreases. In this work the sensing properties of S-G600 and MW600 samples for acetone and LPG were also investigated. Therefore, the operating temperature of both samples for 1500 ppm of acetone and LPG were measured. The operating temperature of S-G600 and MW600 samples for acetone gas were 250 oC and 300 oC, respectively. The operating temperature of both samples was 300 oC for LPG. Then at operating temperature, sensing properties were measured at different gas sensing concentarion (500 ppm-4500 ppm). The results showed for sensing of acetone gas, S-G600 sample has the lowest operating temperature, response and recovery time. Moreover, MW600 sample has most sensivity for acetone gas. It was also obtained MW600 sample had minimum response and recovery time and most sensivity for LPG. The results showed that the selectivity of both samples for LPG is better than acetone.