The thermal energy efficiency, the specific energy consumption, and the emission of exhaust gasses of three different balady bread ovens were investigated, and evaluated. The compared ovens are installed in three different balady bread bakeries namely: - Full-mechanical automatic using solar fuel (MA-L); Semi -mechanical automatic using natural gas fuel (SMA-G); and Semi -mechanical automatic using solar fuel (SMA-L). The comparative tests were deduced under numerous variables included the fuel type, volumetric air/fuel ratio (A/F), and the baking capacity. The obtained results revealed that, the optimum oven thermal efficiency (88.56%) in (SMA-G) bakery was obtained at A/F ratio of 12.24 and flue gases temperature of 276.66° C.  While, optimum thermal efficiencies of 85.54 % in    (SMA-L) bakery, and 86.61% in (M-L) bakery were obtained at similar A/F ratio of 19.76, and at flue gas temperatures of 326,and 304° C respectively. The results also indicated that the least specific fuel energy consumption value (2.03 MJ/ kg flour) was corresponded the (SM-G) bakery. While the highest value (5.38 MJ/ /kg flour) was corresponded the (SM-L) bakery. The results of exhaust gas emission showed that, the emission of sulfur dioxide (SO₂) and nitrogen monoxide (N₂O) were higher in case of operating SMA-L bakery than those of operating MA-Land SMA-G by about 2.09 and 5.85 times respectively. In addition replacing the natural gas instead of solar as a fuel resulted in high reduction the environmental pollution produced from the balady bread bakeries under the Egyptian conditions. Whereas, the emissions of toxic compounds (such as benzene, toluene, xylene, and trichloroethylene (TCE)) weren't detected in case of using natural gas, while, these compounds were 71-9-12-18 and 88-16-18-23 ppm for (MA-L, SMA-L) oven respectively that used solar fuel.