This article contains a brief description of the Codex of Petrarch, which is located in the Czartoryski Library in Kraków. Preliminary analysis proves that the Codex comes from Italy or France. The Czartoryski family bought it in the nineteenth century. The Petrarch Codex contains two incomplete biblical books: Genesis 23:8 - Exodus 14:28, i.e. Hebrew text and Aramaic translation. The analysis is focused on three main aspects: historical, paleographical and linguistics. The detailed analysis proved that the Aramaic text was in some aspects very similar to Targum Onkelos, and in others it was very similar to Targum Pseudo-Jonathan. Most importantly, the text contains an unknown version of Targum Onkelos. Therefore the article also shows morphological and grammatical differences between the official edition of the Targum Onkelos and the text.