The Church offers us different prayers that we can say every day of the week for the faithful departed. These are especially useful for offering a novena on behalf of the dead, or for praying during those seasons of the year (November, in the Western Church; Lent, in the Eastern Church) designated by the Church as times of fervent prayer for the dead.
We should remember the faithful departed on Thursdays by praying this prayer.
Thursday Prayer for the Faithful Departed
O Lord God omnipotent, I beseech Thee by the Precious Body and Blood of Thy divine Son Jesus, which He Himself on the night before His Passion gave as meat and drink to His beloved Apostles and bequeathed to His Holy Church to be the perpetual Sacrifice and life-giving nourishment of His faithful people, deliver the souls in purgatory, but most of all, that soul which was most devoted to this Mystery of infinite love, in order that it may praise Thee therefor, together with Thy divine Son and the Holy Spirit in Thy glory for ever. Amen.