Abstract: The invention relates to an apparatus for drying finely particulate solids in a carrier gas stream conducted along a helical path. The apparatus consists of an externally heated and cooled flow tube centrically surrounding a similarly heated and cooled inner body. Guide means helically arranged in succession in the flow direction are situated between the flow tube and inner body, and are formed as aerofoil-like curved or flat plates and are distributed over the whole length of the inner body. These guide means are designed as a self-supporting structure not secured to the inner body.