Biotransformation of p-coumaric acid by Paecilomyces variotii resulted in the accumulation of a metabolite which was identified as p-hydroxybenzoic acid. We studied the possibility of enhancing this metabolite by various parameters such as varying the concentration of substrate, addition of different nitrogen sources and carbon sources at varying concentration and use of different agricultural wastes as a nutritive medium. Maximum amount of 254.6 ± 9.34 mg/kg of p-hydroxybenzoic acid was detected in the solid medium of corncob on 4th day of incubation using 10 mM p-coumaric acid as a sole carbon source. Consequently, P. variotii can be used as candidate fungi for the production of p-hydroxybenzoic acid. Solid wastes can be managed by using them for biotransformation of pharmaceutically important phenolic acids and hence cut down the cost of production of value-added compounds using a low-cost medium.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-014-0262-5) contains supplementary material, which is available to authorized users.