An advantageous process for pre-treating lignocellulosic biomass to hydrolysable polysaccharide enriched biomass with reduced amount of inhibitors of catalysis comprising steps of: providing a feedstock comprising cellulosic biomass; chopping of cellulosic biomass to have a cellulosic biomass feed material of uniform size; feeding of uniform sized feed material to a horizontal counter current extraction unit; removing excess of water from the feed material obtained from the extraction unit; soaking the extruded feed material obtained from the extraction unit; optionally removing excess of water from the feed material obtained after acid soaking; steam pre-treating the feed material obtained after removing excess of water from the acid soaked feed material; neutralizing the slurry obtained from the steam pre-treating; and optionally saccharifying the neutralized slurry.