Chemiluminescence (CL) was immediately observed after an iron-chlorophyllin aqueous solution was added to an acetonitrile/water mixed solution containing hydrogen peroxide. Quenching of the iron-chlorophyllin complex CL was caused by adding L-ascorbic acid. Based on these facts, a determination method involving small amounts of L-ascorbic acid was developed. As a result, this CL system is able to determine L-ascorbic acid over a wide concentration range of 4.0 x 10(-12) to 4.0 x 10(-4) mol L(-1). Also, coexisting substances, such as sugar and vitamins, did not interfere with the determination. Moreover, the participation to the CL was not observed when using other reducing agents, such as hydroxylamine hydrochloride. As an application for practical use, L-ascorbic acid in soft-drink powder was determined. The experimental value was almost the same as the calculated one (5.30 x 10(-5) mol L(-1)).