This Allied Publication defines a tube furnace test method for determination of a TOXICITY INDEX value for gases released from small specimens of materials@ under sets of specified thermal conditions and analytical parameters specific to various toxic species. Fire effluents produced during tests at 800??are analysed for 8 gases (CO@ CO2@ NOX@ SO2@ HF@ HCl@ HBr@ HCN). Two further gases (formaldehyde HCOH and acrolein CH2CHCHO) are analysed in fire effluents obtained during tests at 350?? Additionally@ analysis for phenol (C6H5OH) at 800??may be required if the TOXICITY INDEX from the remaining gases is close to the acceptance criterion (i.e. greater than 6 and less than 10). Contributions from all 10 (or 11) gases are summed to give a global TOXICITY INDEX. This Allied Publication is intended to form part of the pre-selection screening process for materials and should not be interpreted as an assessment of toxicity hazard under actual fire conditions. The test method is directed at the analysis of a specified set of gaseous species which are commonly present in combustion products of materials used in military applications and which may cause lethality at the time of the fire. It does not address acute mental incapacitation effects@ delayed/long term toxicity@ or toxicity involving particulate combustion products. The set of gaseous species analysed is not exhaustive and other toxic species@ not yet listed@ can be evolved from common materials. The current list represents a set designed to give a general assessment of the toxic hazard.