The present invention pertains to a method for consolidated bio processing of lignocellulosic biomass to L-Lactic acid. Particularly, the present invention relates to the production of L-Lactic Acid from low cost non edible feedstock lignocellulosic biomass. More particularly the present invention relates to the process for one step production of L-Lactic Acid from lignocellulosic biomass using thermophilic bacteria Paenibacillus macerans IIPSP3 (MTCC 5569), which is not only capable of hydrolyzing cellulose to glucose but also further fermenting it to L-Lactic Acid under aerobic conditions, without any growth inhibition in presence of lignin. The present invention provides a process which has less chances of contamination, as the fermentation is carried out at higher temperatures and is economically attractive, as preferably no external enzyme loadings are required.