Municipal solid waste was processed by a mechanical–biological end composting process both in pilot and full‐scale plants. The organic fraction obtained by mechanical treatment (fraction → < 50 mm) was processed at a high composting rate for 37 days followed by a curing phase of 79 days. Process parameters were registered and kept in an optimal range (oxygen > 140 ml l−1, temperature < 65°C, moisture > 500 g kg−1 w.w.). After the high‐rate phase, the products obtained showed a high degradation coefficient and good biological stability (ΔVS = − 54.75% and − 35.35%, DRI = 300 and 500 mg O2 kg−1 VS h−1, respectively, for pilot and full‐scale plants) especially for the pilot plant, indicating that it is not possible to obtain the same performance for a full‐scale plant as obtained under laboratory conditions. Nevertheless, the successive curing phase showed less of a discrepancy between the two processes (ΔVS = − 66.33% and − 56.87%, DRI = 280 and 360 mg O2 kg−1 VS h−1, respectively, for pilot and full scale plants). The quality of the stabilized product was tested by biogas production tests. As expected, a sample processed in the pilot plant produced less biogas (26 l kg TS−1) than that obtained at full scale (40 l kg TS−1). An unprocessed sample produced less biogas owing to the production of organic acids, which, by lowering the pH, inhibit the generation of gas.