The present article analyzes the legal nature and provisions of an arbitration agreement, which in Poland is commonly and statutorily defined as an arbitration clause. An arbitration agreement is defined as an act whereby the parties submit a dispute
for resolution by an arbitration court and at the same time exclude the jurisdiction of a common court in civil cases. The legal nature of an arbitration agreement is strictly related to the legal nature of arbitration. Under Polish legislation, some recognize the arbitration agreement as a substantive civil law agreement, others consider it to be an agreement in the field of civil procedure, and still others attribute it to a mixed material and procedural nature. The author of the article supports the mixed nature
of the arbitration agreement and the material and procedural theory of arbitration. Furthermore, the article analyzes the content of the arbitration agreement. The article highlights among others, the obligatory provisions resulting from Art. 1161 of the Code of Civil Procedure [PL: kodeks postępowania cywilnego] and optional provisions that are shaped within the autonomy of the will of the parties.