Rudolf Augustus, a member of the House of Welf, ruled as Duke of Brunswick-Wolfenbüttel from 1666 until his death. In 1685 he co-ruled with his younger brother Anthony Ulrich. His interests were more inclined towards studies and hunting, so he appointed his politically savvy brother Anthony Ulrich as governor. During his reign, he concentrated on the Baroque expansion of the ducal residence, including the "Alter Weg" ("Old Way"), which connected the cities of Brunswick and Wolfenbüttel. He died in the hunting lodge Hedwigsburg in 1704. He had three daughters with his first wife, Christine Elizabeth, and after her death he entered into a morganatic marriage with Rosine Elisabeth Menthe, but they had no children together.

Prince Rudolf August (1627-1704) was the reigning Duke of Brunswick-Wolfenbüttel from 1666 to 1704. Its coinage was one of the most significant in the German-Roman Empire in the 17th century. During the reign of Rudolf August, the Duchy of Brunswick-Wolfenbüttel underwent significant economic development. The duke supported trade and industry and introduced the system of manufactories. Thanks to the economic development, the coinage of the duchy also flourished. Rudolf August's coinage consisted primarily of gold and silver coins. The most significant of the gold coins was the 24-piece ducat series, which was produced from 1666 to 1704. The ducats were of high quality and were widespread in the German-Roman Empire. Among the silver coins, the most significant was the thaler series of 30 pieces, which were also made from 1666 to 1704. The thalers were also of high quality and were among the most valuable coins of the German-Roman Empire. Rudolf August's minting contributed significantly to the economic development of the Duchy of Brunswick-Wolfenbüttel. Coins of the duchy became widespread in the German-Roman Empire and contributed to the growing economic and political influence of the duchy.