Microwave irradiation can significantly speed up solvent evaporation in crystallization processes, resulting in rapid crystallization and reduced particle size. A single-mode microwave setup was used for evaporative crystallization of the model pharmaceutical compound, niflumic acid. Production of crystals by microwave irradiation offers a novel way to particles for drug formulation solving formulation problems of drugs with low solubility and permeability in class II of the Biopharmaceutics Classification System. In this work, niflumic acid was produced using microwave irradiation and conventional heating. The final product size, as measured by a particle size analyzer, was reduced when increasing the evaporation rate using microwave irradiation. X-ray diffraction proved that the crystal form after microwave-assisted crystallization remained unchanged.