IEC 61882:2016 is available as IEC 61882:2016 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition. IEC 61882:2016 provides a guide for HAZOP studies of systems using guide words. It gives guidance on application of the technique and on the HAZOP study procedure, including definition, preparation, examination sessions and resulting documentation and follow-up. Documentation examples, as well as a broad set of examples encompassing various applications, illustrating HAZOP studies are also provided. This second edition cancels and replaces the first edition published in 2001. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - clarification of terminology as well as alignment with terms and definitions within ISO 31000:2009 and ISO Guide 73:2009; - addition of an improved case study of a procedural HAZOP. Keywords: HAZOP, risks and operability problems