Kock is located a few kilometers north of the Wieprz river, approximately 150 meters above sea level, near the Łuków Lowland (Równina Łukowska). In 1952–1954 it was the seat of Gmina Białobrzegi. The town first appears in chronicles in 1258 as Cocsk. In the 15th century, it was called Kocsko or Koczsko, and in 1787, its name was spelled Kocko. Current form has been in use since the 19th century, and the word Kock either comes from the nast name or a nickname Kot (a person named so founded the town), or from a plant called kocanka (Helichrysum arenarium), which grows abundantly in the area.
Kock has been recognized as an established community since the 12th century. It received its city charter in 1417, by King Władysław II Jagiełło, who granted the charter upon request of Jakub, the Bishop of Płock. In 1518 the town belonged to Mikolaj Firlej, Crown Hetman and the Voivode of Sandomierz. The Firlej family owned Kock until the second half of the 18th century, and at that time the town became an important center of the Protestant Reformation in Lesser Poland. Around the year 1750 Kock passed into the hands of Princess Anna Jabłonowska of the Sapieha family, who invested a lot of money and energy into the town, ordering the construction of a town hall, a palace and a church. Furthermore, she established the market square (or rynek). The residents of the town participated in the January Uprising, for which the Russians deprived Kock of its town rights (1870, recovered in 1915). Several important battles took place at Kock in the 19th and early 20th centuries:
After World War I Kock belonged to Lublin Voivodeship. The town, located away from rail connections, stagnated. Furthermore, in 1927 large parts of it burned in a fire. Kock was one of centers of the Home Army, whose units (27th Volhynian Home Army Infantry Division freed the town on July 22, 1944. Afterwards, the Soviets disbanded Polish soldiers, and in the resulting civil war, Kock was captured by anti-Communist resistance (May 1, 1945).