The present invention generally relates to a system for preparing reduced graphene-cobalt chromate composite for humidity sensor applications comprises a first glass beaker for pouring 3-7 grams of sucrose; a preheated muffle furnace for heating the first glass beaker containing sucrose for 5-15 minutes at 450-500° C. in an oxygen environment and obtaining the black foam of rGO after hydrating the sugar; a second glass beaker for mixing 3-7 grams rGO, 3-7 grams carbamide, 3-7 grams cobaltous, and 3-7 grams chromium nitrate and dissolving with double-distilled water; and a magnetic stirrer for stirring the mixed solution for 450 minutes to generate a homogenous solution and burning the uniform mixture at 425° C. in the preheated muffle furnace for 20 minutes to obtain graphene-cobalt chromate composite.