TCCA（Trichloroisocyanuric acid） is an organic compound with the formula (C₃Cl₃N₃O₃). It is used as an industrial disinfectant, bleaching agent and a reagent in organic synthesis.This white crystalline powder, which has a strong "chlorine odour," is sometimes sold in tablet or granule form for domestic and industrial use. Salts of trichloroisocyanuric acid are known as trichloroisocyanurates.

The compound is a disinfectant, algicide and bactericide mainly for swimming pools and dyestuffs, and is also used as a bleaching agent in the textile industry. It is widely used in civil sanitation for pools and spas, preventing and curing diseases in animal husbandry and fisheries, fruit and vegetable preservation, wastewater treatment, as an algicide for recycled water in industry and air conditioning, in anti shrink treatment for woolens, for treating seeds and in organic chemical synthesis.

Trichloroisocyanuric acid as used in swimming pools is easier to handle than chlorine gas. It dissolves slowly in water, but as it reacts, cyanuric acid concentration in the pool will build-up.