This, and a subsequent paper consider the re-use of thermoset recyclate as a functional filler for polypropylene. Emphasis is given in this communication to characterisation of feedstocks produced by size-reducing dough moulding compound (DMC) and woven glass phenolic laminate (GWP). The physical properties of these microcomposite particulates have been analysed to determine their size, morphology, structural integrity and thermal stability at polypropylene melt processing temperatures. The DMC recyclate was found to have a glass fibre content of 26(w)/o, with fibres up to 10 mm retained in the comminuted particulates. The material is stable up to similar to 220 degreesC. The GWP, however comprised 79(w)/o of woven glass platelets which are largely preserved in the size-reduced recyclate. The material is thermally stable up to 290 degreesC.