Apparatus for classifying objects in an input waste stream comprises a hyperspectral sensor, means for moving objects in the input waste stream relative to the sensor and through a sensing region thereof, and processing means for classifying objects in the input waste stream on the basis of signals output from the hyperspectral sensor to the processing means. The apparatus allows classification of objects composed of one of a wide range of materials and also provides for discrimination of objects comprising different grades of the same material.