The invention provides a system for pyrolysing organic waste. The system comprises a conical housing (4) configured to temporarily, substantially hermetically, enclose the waste and a mixing device provided with a drive shaft rotatably mounted relative to the housing and a conical mixing body (25) configured inside the housing to fluidise the waste, which mixing body fixedly attached substantially does not touch the housing. The system further comprises heating means (24) for heating the side wall of the housing. This system makes it possible to carry out the processing of organic waste in a batch process. The mixing body prevents a portion of the waste from sticking together by fluidising the waste and keeping it fluidised, whereby the heat generated by the heating means can gradually spread through the waste inside the housing.