Prepare a dilute solution of sulfuric acid with a concentration of about 20 percent. Measure 200 cubic centimeters of concentrated sulfuric acid using a measuring cylinder and mix it with 800 cubic centimeters of water in a beaker to make one liter of a 20-percent sulfuric acid solution. Cool the solution till it is ice cold by placing the beaker into a bath with ice water.
Measure a liter of 20 percent sodium peroxide solution using the measuring cylinder. Make sure you clean the cylinder properly before using it on the sodium peroxide to remove traces of sulfuric acid. Take the ice-cold sulfuric acid and transfer it into a bigger beaker. Slowly pour the sodium peroxide solution into the larger beaker in small doses, while watching the reaction.
Let the mixture settle down after you have poured all the sodium peroxide solution into the larger beaker. Crystallization of sodium sulfate will occur, leaving behind dilute hydrogen peroxide in solution of 20-percent concentration. Decant the hydrogen peroxide solution into a dark bottle through a sieve to avoid any sodium sulfate from falling in as well.
Store the hydrogen peroxide bottle in a dark place away from reach of children, such as a medical cabinet. Avoid exposing the solution to high temperatures to prevent it from decomposing back to hydrogen and water.