Due to lack of scientific universal guidelines for Antarctic soils, remediation targets for hydrocarbon contaminated sites do not exist. In Antarctica several aged sites exist that are comprised of residual fuels, such as Casey Station. Residual fuels are the different forms of hydrocarbons which may have degraded or transformed to less toxic products over time. These fuels may comprise of long chain alkanes through to unidentified cyclic fractions and their toxicity and degradation potential are still unknown. Microbes dominate Antarctic soils therefore studies aimed to understand the microbial ecotoxicity of aged fuels is necessary. Our aim was to investigate the microbial ecotoxicity of soils from Casey Station. To do so, we setup ex-situ mesocosms with different concentration of fuel mix ranging from 250 -10,000 mg/kg. The fuel mix used was five hydrocarbon mix (Prisane, Docosane, Naphthalene, 2-Methylnaphthalene and Decalin) and these hydrocarbons were similar to that present in Casey soils. The mesocosms were incubated over 21 months, with samples taken in regular interval and the response of microbial community was examined using next generation sequencing and multifluidic QPCR. Furthermore, given the potential for relic DNA to exist, we will present a comparison of the active community and total community (DNA). Information about community dynamics in response to various concentrations of spiked aged fuel will be used to develop soil quality guidelines for remediation of aged fuels in Antarctic soils.