The present invention provides a method of deploying a eutectic alloy based tool within an oil/gas well. The method comprising providing a eutectic alloy based downhole tool comprising a tubular body with eutectic alloy located on an outer surface thereof, said tool having an outer diameter with a clearance from the inner diameter of the well. The downhole tool is delivered to a target region within an oil/gas well where the tool is to be deployed. Once the tool is in position within the well a tubular expanding tool is run through the interior of the tubular body so as to increase the outer diameter of the sealing downhole tool and in so doing reduce the clearance between the alloy and the well. Following the expansion of the tubular body a heater is deployed within the tubular body proximal to the alloy and operated to melt the alloy. The alloy is then allowed to cool and resolidfy, whereby the tool is sealed in place within the target region of the well using the alloy.