Gas inerting process is a great hazard for chemical tanker ships and utmost care is required considering the harmful effects to humans' health. Most of the chemical tanker ship-owners face near-miss or accident (asphyxia/fire/explosion) during gas inerting process on-board ship. The consequences of the process may pose catastrophic results such as explosion, fire or asphyxiation. Therefore, a detailed risk assessment is required to enhance the process of safety during the carriage of chemical cargo and minimize potential consequences. To address this concern, the paper aims at conducting a systematic probabilistic analysis of asphyxiation risk during gas inerting process in chemical tanker ship. In the paper, a Bayesian belief network (BBN) method is used to deal with causality and uncertainty arising from the complex interdependence between variables in the probabilistic risk assessment of asphyxiation risk. While BBN enables us to calculate the conditional probability of each intermediate node and leaf node in the graph and perform probabilistic risk assessment with sensitivity analysis, fuzzy logic deals with the translation of linguistic expressions from expert opinion into probability values. The findings of the paper will provide the utmost contribution for chemical tanker ship owners, safety researchers, maritime safety professionals, and HSEQ managers (Health, safety, environment, and quality) to prevent the risk of asphyxiation during gas inerting process in maritime transportation. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.