This document was prepared by Technical Committee CEN/TC 275, Food analysis, Working Group 6, Microbiology, in collaboration with ISO/TC 34, Food products, Subcommittee SC 9, Microbiology, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).This second edition cancels and replaces the first edition (ISO/TS 20836:2005), which has been technically revised.The main changes compared to the previous edition are as follows:— the scope has been extended to include both thermal cyclers and real-time thermal cyclers;— the document type has been changed from ISO/TS to an ISO-Standard;— the physical performance testing method has been described in more detail, the biochemical performance testing method has been taken out;— information for laboratories regarding ISO/IEC 17025 have been included;— the performance testing method has been aligned with ISO/IEC 17025;— compliancy testing has been added;— in Annex C two procedures to set PCR method based specifications have been added.