[1] Mattei was born in Senglea Malta on 24 July 1761.

After being ordained priest, Mattei was appointed as one of the knights of St John's Conventual Chaplains because of the high regard they had for him.

After the French left Malta the British looked with favor upon him.

[3] He was opposed by Francesco Saverio Caruana who himself wanted to be bishop of Malta.

Mattei died on 14 July 1829, at age 67, and Caruana would eventually succeed him.