A method was developed by which Nile-Blue (2381853) could be used as a redox indicator in titrations with ammonium-hexanitratocerate in perchloric-acid (pCl) medium. Solutions of 0.1 Normal (N) iron (7439896), hexacyanoferrate (13408634), arsenic (7440382), vanadium (7440622), uranium (7440611), molybdenum (7439987), and hydroquinone (123319) were prepared and treated with varying amount of 70 percent pCl to give the required overall acidity when diluted to 50 milliliters (ml), and with 0.15ml of 0.1 percent Nile-Blue solution. The mixtures were titrated with 0.1N solution of ammonium-hexanitratocerate. In titration of iron, the color change at endpoint was not satisfactory in media of more than 1.0N pCl, nor when the amount of iron was below 0.05 millimole (mmole). The endpoint was not easily detected in the titration of 0.1N hexacyanoferrate, but was easily detected in 0.05 and 0.01N hexacyanoferrate in 0.1 to 0.5N pCl, provided the amount hexacyanoferrate did not exceed 0.75mmoles. Arsenic could be titrated up to 1.25mmoles using 0.3 to 2.0N pCl and an osmic-acid catalyst, up to 4mmoles using 0.5 to 1.5N pCl and an iodine-monochloride catalyst, and up to 5mmoles using 0.5 to 1.0N pCl and a ferron catalyst. In the first two cases, it was necessary to add the indicator near the endpoint. In the titration of vanadium, the reaction was very slow in 0.1 to 1.5N pCl, but was quite fast in 0.05 to 0.15N pCl plus 3.0 to 5.0N acetic-acid. In the titration of uranium, endpoint detection was difficult for 0.1N uranium, but was easy for 0.05 and 0.01N uranium in 1.0 to 1.2N pCl, provided the amount of uranium was from 0.1 to 0.2mmoles. Molybdenum could be titrated in the range of 0.15 to 1.25mmoles only, using 2.0 to 3.0N pCl. In titration of hydroquinone in 0.5 to 4.0N pCl, color change at endpoint was stable for only 30 seconds.