Various Phosphate solubilising microorganisms (PSM) were isolated from the natural habitats of Populus alba from Lahaul and Spiti valleys of Himachal Pradesh. The PSB isolated belonged to genera Bacillus and Micrococcus while the PSF isolated frequently belonged to species of Aspergillus and Penicillium. The isolates with high efficiency for tricalcium phosphate solubilisation, were further tested for their capacities to solubilise Mussoorie Rock Phosphae (MRP), Udaipur Rock Phosphate (URP) and North Carolina Rock Phosphate (NCRP) at different pH ranges. The bacterial isolate PBC2 (Bacillus) was reported to be highly efficient under alkaline conditions while amongst fungi PFC6 (Aspergillus niger) was solubilising maximum insoluble phosphate under acidic conditions.