The pilot set-up of a horizontal high energy ball mill (Simoloyer(18)) that has been successful in reactive milling, mechanical alloying, and formation of ductile metal-flakes is used for semi-continuous processing of organic solid-solid reactions which proceed rapidly and without wastes in the absence of solvents. 200 g batches were run in the exploratory investigation. Stoichiometric 1:1-mixtures of alpha-(D)-glucose and urea formed the 1:1-complex with quantitative yield after 5 min at a rotor frequency of 900 min(-1). Similarly, the condensation reaction of solid p-hydroxybenzaldehyde with solid p-aminobenzoic acid was complete after 15 min yielding the pure imine derivative in quantitative yield without waste producing work-up procedures. Further scale-up appears possible also with other solid-solid reactions.