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In this work, a co-gasification process of sewage sludge and the poultry litter for hydrogen production was developed which involves gasification, water gas shift reaction, acid gas absorption and combustion for power generation. Based on the situations in Hong Kong, the complete processing system was simulated and optimized by developing a composite sustainability objective. The single objective was obtained by the fuzzy method after collecting the decision-making preferences on product yield, economic cost, safety index, environmental impacts, and exergy efficiency. Optimization results showed the exergy efficiency was 30.75%, and the gas turbine operation was most hazardous. The total life cycle greenhouse gas emission was estimated to be 832.58 tons/day with a hydrogen yield of about 47.92 tons/day according to the systematic analysis. Moreover, a subsidy of 115.65 $/ton waste can achieve a relatively attractive profit for the waste-to-H 2 process, which was validated by an IRR value of 10% and a positive NPV value in 20 years. The economic sensitivity analysis was finished by testing the influence of some key factors. It was indicated that the subsidy fees, H 2 market price, and total equipment cost were relatively more important in the financial profit for this process. [Display omitted] • A systematic waste co-valorisation process for H 2 production is proposed based on the gasification conversion. • Process optimization is finished by stochastic optimization with a constructed sustainability objetive. • Total life cycle GHG emission was 832.58 tons/day with a H 2 yield of about 47.92 tons/day. • The subsidy fees, H 2 market price, and total equipment cost is quite influential to the project economics. • A subsidy of 115.65 $/ton waste should be supported for good economic profit. [ABSTRACT FROM AUTHOR]