A simple potential dfference (PD) test is developed that can rapidly (within ∼ 10 days) provide a chloride diffusion index. The test utilizes a small applied potential difference (10 V dc) to accelerate the transport of chloride ions through concrete. Conventional nonperturbative, concentration difference (CD) tests have been carried out in parallel, with typical test periods of up to 12 months. Fick’s First Law of Diffusion is applied to calculate a diffusion index from the PD test, and the coefficient of chloride diffusion D from the CD test. A close relationship between these two parameters is shown, allowing D to be estimated from the rapid PD test.