This publication is intended to assist those Member States with limited decommissioning expertise, to estimate the overall cost of decommissioning during the early planning stages. The lack of published data has made it difficult to benchmark estimated costs against international practice. The DACCORD (data analysis and collection for costing of research reactor decommissioning) project was established to address this deficiency. Based on the outcome of the three main working groups, this publication provides representative input data and benchmarking data needed for the costing of research reactor decommissioning at preliminary planning stages. All detailed cost cases considered in the DACCORD project are presented in a special format, following a software tool, developed by the IAEA, and which helps to ensure uniformity of the presented data and generally to facilitate the analysis of the available information.