The collecting activity of Bishop Josip Juraj Strossmayer (1815-1905), whose donation of Renaissance and Baroque paintings forms a nucleus of today’s Gallery of Old Masters of the Croatian Academy of Sciences and Arts, is the object of a research based on the archival sources, primarily the abundant correspondence of the Bishop and his intermediaries for the painting acquisitions. Apart in Rome, Bishop had a permanent agent only in Venice, the Rijeka painter Giovanni Simonetti (1817-1880). He did not only buy paintings for Bishop’s collection, but was active as restorer, adviser and a Bishop’s link to the circle of Venetian painters, restorers and connoisseurs, whose activities often spanned from collecting to art dealing as well. Although Bishop’s Venetian acquisitions are not so good documented as his purchases in Rome, on the basis of the comparative analysis of available sources it is possible to reconstruct the procurement circumstances and the provenance of particular paintings.