Introduction Vermicomposting could increase nutrients availability including phosphorus. During vermicomposting, a decomposition of organic substrates leads to the production of several organic acids, such as malonic, fumaric, succinic acids. Microorganisms both in the intestinal organ of the worms and the organic waste have the ability to convert insoluble P into soluble forms. Little information exists about the effects of vermicomposting on rock phosphate (RP) solubilization. Present study was conducted to evaluate the solubilization of powdered RP during vermicomposting. Results Vermicomposting and RP application increased NaHCO3-Pi. Rock phosphate application in vermicomposting significantly increased NaHCO3-Po. Vermicomposting significantly increased NaOH-Pi in all of the treatments. RP application and vermicomposting increased HCl-Pi in both organic sources. Generally, vermicomposting increased HCl-Po. Vermicomposting decreased pH but its effect was more evident in the presence of RP. Vermicomposting increased EC in both organic sources. Conclusion Present study showed that vermicomposting helps to enhance the transformation of P from RP into various organic or inorganic P forms, which would be readily or moderately available, thus, increase the availability of P from both RPs.