The formaldehyde oxidation reaction with use of Fenton’s reagent was conducted in a thermostated container with a volume of 1000 ml. Study of the concentration of ferrous sulphate (FeSO4×7H2O) were 400, 500 and 600 ml wastewater sample containing formaldehyde . The solution was mixed with a magnetic agitator with a velocity of 300 rpm. After FeSO4×7H2O dissolved, an appropriate amount of 30% hydrogen peroxide solution (H2O2) was added.