Soon after their arrival in Osijek, Franciscans built their first church near the Suleiman-han mosque. It was relatively small and built with old wood. Besides the main altar there were probably two side altars: St. Anthony's, and in the early 18th ct. the altar of the Blessed Virgin Mary, because of the statue of Our Lady of Jud.

Since this church had become too small for the growing number of devotees of St. Anthony, the Franciscans asked emperor Leopold I to assign them a piece of land where the mosque stood and the surrounding grounds to erect a bigger, more appropriate church on it.

After they were granted their request the first official Osijek guardian P. Antun from Osijek began building the monastery church. The corner stone was consecrated in 1709 by the Bosnian bishop Đuro Patačić. Nothing more is written about the construction process because at that time monastery memorials weren't kept. On account of a document from the monastery archives we know that the church was built and decorated by 1732, because on the 22nd Sunday past Pentecost monastery church of the Holy Cross in Osijek was festively consecrated by Sigismund Berenny, auxiliary bishop to the archbishop of Ostrogon. On that occasion he consecrated the main altar and four more altars: the first to honour the Immaculate Virgin; the second to honour St. Anne; the third to honour St. Anthony; and the fourth to honour St. Catherine. The consecration was performed on 11 November, 1732.

These two events were marked by placing a gold-engraved marble plaque on 3 August 1737 above the main church door. The building of the church lasted for 24 years because Franciscans were erecting it with help from citizen church members, devotees of Our Lady of Jud and St Anthony of Padua. Some of these pious Osijek handicraftsmen, wishing to be buried in that church, donated money in greater amounts. The Franciscans continuously remembered their benefactors in their prayers.

During the 18th ct. there were some changes in the church of the Holy Cross. The main altar, made in Vienna 1726, had originally been placed in the centre of the sanctuary, because the choir had been behind it. During restoration of 1752 it was moved closer to the wall in order to make more space, and into the redecorated altar was placed the miraculous statue of Our Lady in richly adorned glass case, that had previously stood on the side altar of the Mother of God. 1770 the main altar was again pushed off the back wall, as it stands today. As far as we know, the church was restored in 1917, too.

The monastery church of the Holy Cross was constructed in the usual baroque manner, but very simple, in direction east-west. The sanctuary is in the east, and the main entrance in the west. There is also a side door in the south. It is a little over 30m long and 13m wide. The front part of the sanctuary and the tower on the left are probably remains of an older church. The facade is split in two, 17.4m long, a simple surface with a cornice. The church has recently been restored on the outside.

At the left side entrance is Our Lady of Lourdes Chapel. At 4m height the front has two niches with statues of St. Francis of Assisi and St. Roch, patron saint against the plague and the patron saint of the Third Order. The upper front part ends in a typical baroque pyramid. On the left of the sanctuary there is a steeple, 38m high, with four bells, probably raised on Turkish minaret foundations. Thanks to bishop Summa, whose bust and epitaph can be seen in the church, a diocesan cross is placed on the church roof, as well as on the spire.

The sanctuary is spacious (10m x 10m), and originally had a sacristy in place of today's burial crypt. It has a three-sided end with a window on the northern and on the southern side. There are two big paintings in the sanctuary: Archangel Michael and Three Kings without Baby Jesus. The vault over the nave of the church, space intended for the congregation, is decorated by paintings showing Jesus taking the Cross; Jesus meeting His Mother; Jesus being taken off the Cross; and Veronica offering Him her towel. There are six lateral altars in the nave. Three are on the north wall: St. Francis, St. Joseph, and St. Catherine, and three on the south wall: St. John Nepomuk, St. Anthony, and St. Anne. On the south wall there is a wooden pulpit, almost imperceptible, that can be approached by a hall behind the church leading to the choir. A wooden classicist confessional, made in 19th ct., stands on the south wall. Ten-rank organ is placed on the choir. The first was put there by Antun Römer in 1762. In 1908 it was replaced with a new one, Heferer organ. It was restored and tuned in 2002. The choir is embellished with a baroque railing. Several stained-glass windows decorate the church: on the choir – the biggest one in the middle depicting St. Cecilia, the one on the right depicting singing angels, and the one on the left angels playing musical instruments; rosettes are placed above the altar; ornamented Cross on the north wall; three saints on the south wall above the side entrance; and in the sanctuary a stained-glass window depicting St. Francis with St. Clare. You can see stained-glass windows in the Our Lady of Lourdes Chapel as well: on the east side St. Elisabeth, and on the west St. Aloysius. Valuable liturgical vessels are mentioned in the description of the church of the Holy Cross: chalices, monstrance, ciborium, reliquary, thurible, and a crosier from the legacy of Summa, the archbishop of Skopje).