In the present investigation, an attempt was made to develop a liquid inoculant using osmoprotectants for phosphate solubilizing bacterium (Bacillus megaterium). Liquid inoculant-2 containing osmoprotectants viz., Polyvinyl Pyrrolidone (PVP), glycerol and glucose supported higher viable population (log 10 10.50 CFU/ml) and endospores (log 10 9.21 CFU/ml) up to a storage period of 6 months. It also supported higher viable cells on cowpea seed (log 10 4.50 CFU/ml) and also enhanced the P-uptake and total biomass of cowpea significantly.