Provided are a barrier coating composition and a method of forming photoresist pattern by an immersion photolithography process using the same. The barrier coating composition includes a polymer corresponding to formula I having a weight average molecular weight (Mw) of 5,000 to 100,000 daltons and an organic solvent, ##STR00001## wherein the expressions 1+m+n=1; 0.1.ltoreq.1/(1+m+n).ltoreq.0.7; 0.3.ltoreq.m/(1+m+n).ltoreq.0.9; and 0.0.ltoreq.n/(1+m+n).ltoreq.0.6 are satisfied; Rf is a C.sub.1 to C.sub.5 fluorine-substituted hydrocarbon group; and Z, if present, includes at least one hydrophilic group. Compositions according to the invention may be used to form barrier layers on photoresist layers to suppress dissolution of photoresist components during immersion photolithography while allowing the barrier layer to be removed by alkaline developing solutions.