Laboratory experiments were carried out to study the effect of some integrated factors on solubility of phosphate rock (PR) obtained from two locations which were Abou Tartour and El-Sibaia Gharb as well as tricalcium phosphate. PRs  were crushed to pass through a 1.18-mm sieve and separated into 7 particle diameters of  500, 250, 212, 125,75 and 45 µm. Scanning Electron Microscope “SEM" and X-ray diffraction were done. P-solubility was assessed using water and 5 acids of formic (FR), Acetic (AC), tartaric (TR) oxalic (OX) and citric (CT) (each of 2%). P in Abou Tartour samples was mainly as calcium phosphate hydroxide “Ca₅(PO₄)₆ OH. Other crystalline were silicon oxide SiO₂, calcium carbonate CaCO₃ and calcium di-hydrogen phosphate hydrate Ca H₂PO₄. P in El-Sibaia samples was mainly in form of Brushite. P contents (g kg^-1) were 0.2 to 0.6 water-soluble, and 10 – 17 for Olsen extract. Ranges for the acid-extractants from the two PRs were 39-44 for CT, 25-41 for AC, 27-49 for TR, 14-28 for OX and 32-52 for FA. A tendency to increase with decreased particle size occurred. Practical aspects could be inferred regarding the use of PR for fertilization.