A process for making substantially water- and dust-free anionic surfactant granules of high bulk density involving: (a) providing a starting material containing a water-containing paste of a monoglyceride (ether) sulfate having a solids content of at least 20% by weight, based on the weight of the paste; (b) providing a horizontally mounted thin-layer evaporator with rotating internals; (c) providing a negative temperature gradient within the evaporator; (d) passing air into the evaporator in countercurrent to the flow of starting material; and (e) simultaneously drying and granulating the starting material by passing it through the evaporator to form anionic surfactant granules having a residual water content of below 2% by weight.