One of the most important tasks for historians is to criticize sources of information, first of all the written ones since their authors tended to be judgmental as a rule. To solve this problem, it is necessary to use alternative sources of information. This research was conducted in order to verify the «Augustan History», i.e. the information regarding the usurpation of Proculus. For this purpose two antoniniani series of his coinage are published. The very fact of their existence can convince us in the reality and relative duration of the Proculus’ reign. It can be assumed that the first series of his coins was mint in Lugdunum, in the early period of his usurpation. On the reverse of the Proculus coins the legend «VICTORIA AVG» was engraved. In such way the Emperor’s victory over the Alemanni was celebrated. The second coin series could be minted in the last period of his reign, when he left Gallia Lugdunensis and was seeking support from the Franks. The legend «PAX AVG» appeared on his coins. I suppose that at that time, Proculus was seeking reconciliation with Probus. Hence it is possible to conclude that the «Augustan History» information about Proculus is quite reliable. The results of the research are brought forward for scientific discussion.