Ten most efficient phosphate solubilizing bacteria and three fungi (PSM) isolated from maize rhizosphere were studied for biochemical characteristics. PSM were grown in vitro for seven days on Pikovskaya,s medium and following analyses were carried out i.e. solubilization index, pH change, phosphorus (P) solubilized, P immobilized and organic acids produced under in vitro conditions. P solubilization index of these isolates ranged from 1.63-3.29. Drop in pH of the medium ranged from 7 to 3.2 with the continuous growth of these isolates for seven days. Study showed that more P was immobilized (0.2-0.46%) than solubilized (0.088-0.22%). Bacteria were found to be more active than fungi in conversion of insoluble P to soluble P. Citric and oxalic acids were two common organic acids produced by PSM. Correlation studies suggested that besides organic acids there might be other factors responsible for P solubilization