A novel method for synthesizing a hydroprocessing catalyst utilizing sustainable, bio-sourced waste materials, specifically cow dung and bat guano, to replace expensive synthetic chemicals. This invention describes preparing a crystalline transition metal molybdotungstate material (MMoWO) where pyrolyzed cow dung acts as a foundational, high-surface-area template rich in silica and alumina. Simultaneously, bat guano serves as the mineralizing solution, providing trace metals (M, Mo, W) and natural complexing agents necessary for controlled crystallization during a solvothermal reaction. The resulting catalyst demonstrates superior structural stability and enhanced coking resistance, making it highly effective for hydrodesulfurization (HDS) and hydrodenitrification (HDN) in the refining of sour crude oils, offering economic and environmental advantages over prior art.