Significant financial and environmental consequences often result from line leakage of oil product pipelines. Product can escape into the surrounding soil as even the smallest leak can lead to rupture of the pipeline. From a health perspective water supplies may be tainted by oil migrating into aquifers. A joint academic-industry research initiative funded by the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) has lead to the development and refinement of an acoustic basedfree-swimming tool which is capable of detecting leaks as small as 0.03 GPM in oil product pipelines and has proven to record leaks in natural gas pipelines. The tool swims through the pipeline being assessed and produces results at significantly reduced cost to the end user compared to current leak detection methods. GPS synchronized GIS-based above ground loggers capture low frequency acoustic signatures and digitally log the passage of the tool through a pipeline. Thispaper presents the development laboratory and field validation testing of thetool for oil and gas pipeline integrity.Key words: Leak detection Integrity verification Pin hole leaks