Abstract: The present invention relates to an insulating coating composition, a substrate coated with such insulating coating composition and a method for protecting a substrate by using the insulating coating composition. The insulating coating composition comprises at least a) chemically toughened epoxy resin component, wherein the ratio of chemically toughened segments, which are elastomeric segments and bonded via chemical reaction on the epoxy resin, is in a range of 20-49 wt %, based on the total weight of said chemically modified epoxy resin component; b) a curing agent; c) reinforcing fibers; and d) low-density fillers with a density ranging from 0.05-0.7 g/cm3, preferably 0.08-0.5 g/cm3, more preferably 0.1-0.4 g/cm3.