Lord, have mercy on us. Christ, have mercy on us.
Lord, have mercy on us. Christ hear us. Christ, graciously hear us.

God the Father of heaven, Have mercy on us.
God the Son, Redeemer of the world, Have mercy on us.
God the Holy Spirit, Have mercy on us.
Holy Trinity, one God, Have mercy on us.

Holy Mary, Pray for us. (repeat after each line)
Glorious Mother of the King of kings,
St. Thomas,
Worthy child of the Queen of Virgins,
St. Thomas most chaste,
St. Thomas most patient,
Prodigy of science,
Silently eloquent,
Reproach of the ambitious,
Lover of that life which is hidden with Christ in God,
Fragrant flower in the garden of St. Dominic,
Glory of the Friars Preachers,
Illumined from on high,
Oracle of the Church,
Incomparable scribe of the God-Man,
Perfect in the school of His Cross,
Model of perfect obedience,
Endowed with the true spirit of holy poverty,

Lamb of God, you take away the sins of the world, Spare us, O Lord.
Lamb of God, you take away the sins of the world, Graciously hear us, O Lord.
Lamb of God, you take away the sins of the world, Have mercy on us.

What have I in heaven, or what do I desire on earth? That you are the God of my heart, and my portion forever.

Let us pray, O God, who ordained that St. Thomas should enlighten your Church, grant that through his prayers we may practice what he taught. Through Christ our Lord. Amen.

Source: Kyrie Eleison — Two Hundred Litanies by Benjamin Francis Musser O.F.M., The Magnificat Press, 1944

Read about the life of St. Thomas Aquinas.