A fluid bed apparatus for coating solid particles. The apparatus includes a housing having upwardly extending walls surrounding a perforated base plate, a nozzle for atomizing a coating liquid, the nozzle being provided in the upwardly extending walls, and a device for providing fluidisation gas through the perforations of the base plate for the maintenance of a fluidised layer. The coating liquid nozzle is provided in a channel for co-current introduction of a dispersion gas, the channel debouching into the fluid bed through an orifice having a radius of 5 mm or more. The apparatus provides for the production of particles having smooth surfaces, high yield and a low tendency to form agglomerates.