Abstract: A process for the development, following imagewise exposure, of two component diazotype material in sheet form constituted by a base carrying a light-sensitive coating containing a diazonium salt, a coupler, and an acid coupling inhibitor, said process comprising, while advancing the material continuously at a rate of 1 to 20 meters per minute, first applying to the exposed light-sensitive coating a non-volatile alkaline, inorganic developer liquid having a pH value of at least 10 at a coating weight between 2.0 and 8.0 grams per square meter to effect, in the unexposed areas of the material, coupling between the diazonium salt and the coupler, then subjecting the material to heat sufficient to dry it and finally applying to the light-sensitive coating a dilute acid solution at a coating weight between 2.0 and 8.0 grams per square meter, said acid solution containing sufficient acid not only to neutralize alkali retained in the material but to leave the emerging material in a substantially acid condition.