A pilot-scale industrial microwave unit operating at 2450 MHz was used to test whether microwave treatment can control Tribolium castaneum (Herbst) populations infesting stored rye, Secale cereale L. (Poaceae). Tests were performed in samples of rye (50 g) with 14%, 16%, or 18% moisture content. Samples containing T. castaneum eggs, larvae, pupae, or adults were exposed to 200, 300, 400, or 500 W for periods of 28 or 56 s, resulting in final surface temperatures ranging from 47.2 to 83.9 °C. Eggs were most vulnerable; adults were least vulnerable. Subsequent tests showed that microwaves reduced rye germination and flour yield. No effect of treatment on grain protein content, falling number, sodium dodecyl sulfate sedimentation volume, mixograph and farinograph dough development times, or baking properties was detected.