During 1997 two different types of coal mine inertisation equipment were trialed in separate underground coal mines in Queensland. In April 1997 tests of the Polish developed GAG-3A inert gas generator were carried out at the Collinsville No 2 Coal Mine. These demonstrations indicated that the GAG-3A device was applicable in underground coal mines and that with respect to inertisation rate the device outperformed all other currently available techniques. The unit was assembled rapidly and operated safely during surface and underground trials and no mechanical problems were encountered with the device. The GAG-3A is not suitable for every fIre scenario particularly if large volumes of fresh air are being drawn into the mine(where multiple units may be required), but with respect to the selection criteria developed by the Moura Implementation Process Task Group 5 criteria, the unit performed up to the specifications required. In May 1997 tests were carried out at the Cook and Laleham Collieries using a Tomlinson diesel boiler. These demonstrations indicated that a low volume generator, such as the boiler, can proactively inert a large goaf area effectively. At Cook a volume of approximately 700 000 mJ was inerted over 10 days and at Laleham an area of approximately 70 000 m3 was inerted over 2 days. The boiler is not suitable for emergency use, due to the low flow rate of inert gas generated (approximately 0.5 mJ/s). There was no significant seam gas present during either trial. Both test programs were financially supported by ACARP and the Department of Mines and Energy. BHP , Shell, and MIM also contributed to the GAG-3A project and Cook Resources Mining contributed to the Tomlinson boiler project.