Bromocresol Green is shown to be an anodic corrosion inhibitor for zinc metal, Bromothymol Blue and 5-sulpho-salicylic acid are cathodic inhibitors and Alizarin is a mixed inhibitor. Langmuir adsorption isotherms show that surface adsorption is the mechanism in each case. The Tafel slopes were measured and galvanostatic polarization used to determine corrosion rates in the presence of the inhibitors and dilute acid. Bromocresol Purple acts as a corrosion accelerator. -- AATA