In this paper we consider a variant of the flexible job shop scheduling problem with uncertain task durations modelled as fuzzy numbers. We propose a cooperative coevolutionary algorithm to minimise the schedule's makespan, with two di fferent populations evolving the two main aspects that conform a solution: machine assignment and task relative order. Additionally, we incorporate a specifi c local search method for each population. The resulting hybrid algorithm, called CELS, is then evaluated on existing benchmark instances, comparing favourably with the state-of-the-art methods.Gobierno de España (FEDER TIN2010-20976-C02-02 and MTM2010-16051)EUROFUSE'2013 Workshop on Imprecision and Uncertainty in Preference Modeling and Decision Makin
