A method of manufacturing heat-sensitive pharmaceutical powder is disclosed. The original pharmaceutical substances are dissolved in a solution or suspended in a suspension, which is sprayed through an atomizing nozzle and frozen in a cold gas phase or liquid nitrogen atomized directly in the spray-freeze chamber or gas jacket at the same time (for cooling purposes). The particles are freeze-dried at roughly atmospheric pressure in a down-stream fluid flow with exit filter thereby to remove moisture entrapped on or inside the frozen particles. The system has applicability for forming other powders.