The invention concerns a spray nozzle for a fluidized bed device, said nozzle comprising a central liquid outlet (15) for a liquid coating agent and an annular air outlet (17) for conveying spraying air coaxially. An enclosing body (1) having a central recess (4) is maintained in a wall of the box of the fluidized bed device. Said enclosing body (1) is connected to a spraying air source through an air duct (6) and an axially mobile nozzle head (14) is centrally mounted inside said enclosing body (1). Said nozzle head (14) is connected to a liquid coating agent source through a liquid duct (10), said liquid duct (10) having a flexible tubular section (12) and being centrally guided inside the air duct (6).