Legacy arsenic contamination from past mining operations remains an environmental concern in lakes of Yellowknife (NWT) due to its post-depositional mobility. Warmer temperatures associated with climate change may impact arsenic diffusion from lake sediments either by direct effect on diffusion rate or indirect effects on microbial metabolism and sediment redox conditions. This thesis assessed the influence of warmer temperatures on arsenic diffusion from contaminated sediment of two lakes using an experimental incubation approach. Yellowknife Bay sediments (clay, 10 % organic matter, and arsenic = 1700 µg/g) differed from sediments of Lower Martin Lake (~70 % organic matter and arsenic = 822 µg/g). Duplicate sediment batches from each lake were incubated for four weekly temperature treatments (5 ℃ to 20 ℃ at 5 ℃ intervals) under oxygenated conditions and regularly sampled for water chemistry. Temperature had no influence on arsenic flux from either sediment type, other factors must be considered.