Reaction accelerating agent

A method for measuring hydrogen peroxide, comprising the step of using peroxidase and a peroxidase reaction accelerating agent,

• wherein the peroxidase reaction accelerating agent is represented by any of the following formulae:
• wherein
• each X is independently selected from the group consisting of —H, —Na, —K, and —Li;
• and
• each Y is independently selected from the group consisting of —H, —SO3X, and —COOX, or,
• wherein the peroxidase reaction accelerating agent is represented by the following formula:
• wherein
• R1 is a benzene ring or a naphthalene ring which may optionally be substituted with one or more substituents, wherein
• the substituent(s) is selected from the group consisting of —SO3X, and
• and
• X is selected from the group consisting of —H, —Na, —K, and —Li.