Previous static bed ozonation scale-up and demonstration trials have proven the use of ozone as an effective technology for grain protection without affecting its end-use quality. Due to the lack of current availability of high capacity ozone producing generators, grain treatment through static bed ozonation systems are limited to be used in metal silos of capacities smaller than 644-t. Also, the trials have shown that treatment time has to be of no less than 4 d during application in order to be effective for pest control. Therefore, more efficient ozonation treatment systems are needed for proper ozone usage for stored product protection. The primary objective of these research studies was to design and test a semicontinuous counter-flow ozonation and a continuous ozonation flow treatment systems in order to ozonate grain at faster rates based on the concentration-time product (CTP) of ozone required to achieve 100% insect mortality and effective mold reduction in grain. The procedure of the counter-flow semicontinuous ozonation system consisted of removing each grain layer inside a metal silo with a tapered unloading auger after each layer reached the desired ozone CTP. The treated grain is subsequently transported to a storage or shipping silo. The continuous ozonation flow system involves applying high ozone concentrations through a modified grain loading screw conveyor where ozone and grain are moving continuously in the same flow direction. The counter-flow semi-continuous ozonation system was successfully tested and proved to be a technically feasible tool for pest control and mold reduction. The continuous ozonation flow system was proved as an effective tool for treating grain during handling while achieving 100% insect mortality, and effective mold reduction.