Production of high titers of an alkaline, extracellular and thermo-tolerant pectinase by a newly isolated yeast Pseudozyma sp. SPJ was carried out under solid state fermentation. Citrus peel, the inexpensive agro-industrial residue used as substrate, was experienced to be unsurpassed. Response surface methodology was conducted to optimize the culture conditions for Pseudozyma sp. SPJ for hyper production of pectinase. Plackett Burman design was applied to identify the most effective culture variables. Out of nine variables studied, incubation time, moisture content and ammonium sulfate were detected as most important. A full factorial Central Composite Design was used to optimize the levels of these variables, which resulted in 17-fold increase (71.19 IU/g to 1215.66 IU/g dry substrate) in the enzyme yield. The results of analysis of variance and multiple regression analysis implies that the effect of incubation time (p<0.000) and moisture content (p<0.018) is more than ammonium sulfate. And also the interaction of moisture content with ammonium sulfate (p<0.002) is more significant.