O God, through St. Catherine of Siena You teach us the wonderful truth about our own human nature—that we live in You and You live in us. With the help of her prayers may this knowledge help us to advance in virtue and to serve You all our days. We ask this through our Lord Jesus Christ, Your Son, who lives and reigns with You and the Holy Spirit, one God, for ever and ever. Amen.

God of Wisdom, You made St. Catherine of Siena burn with divine love in contemplating the Lord’s Passion and in serving Your Church. With the help of her prayers, may Your people, united in the mystery of Christ, rejoice forever in the revelation of His glory, who lives and reigns with You and the Holy Spirit, one God, for ever and ever. Amen. 

Humble virgin and doctor of the Church, in thirty-three years you achieved great perfection and became the counselor of popes. You know the temptations of mothers today as well as the dangers that await unborn infants. Intercede for me that I may avoid miscarriage and bring forth a healthy baby who will become a true child of God. Also pray for all mothers, that they may not resort to abortion but help bring a new life into the world. Amen.  

Novena:

O marvelous wonder of the Church, seraphic virgin, St. Catherine, because of your extraordinary virtue and the immense good which you accomplished for the Church and society, you are acclaimed and blessed by all people. Oh, turn your benign countenance to me who, confident of your powerful patronage, calls upon you with all the ardor of affection and begs you to obtain, by your prayer, the favors I so ardently desire. You, who were a victim of charity, who in order to benefit your neighbor obtained from God the most stupendous miracles and became the joy and the hope of all, you cannot help but hear the prayers of those who fly into your heart--that heart which you received from the Divine Redeemer in a celestial ecstasy. Yes, O seraphic virgin, demonstrate once again proof of your power and of your flaming charity, so that your name will be ever more blessed and exalted; grant that we, having experienced your most efficacious intercession here on earth, may come one day to thank you in heaven and enjoy eternal happiness with you. Amen.

Dominican Tertiary and Doctor of the Church, you were full of wisdom, the special gift of God, and you knew how to guide even pontiffs, as well as how to extinguish fiery passions and restore true peace among people. How inspiring your spiritual writings and how heroic your abstemious life! Fires are today unfortunately all too common - including those caused by criminals. Please protect and encourage firefighters in their heroic efforts to save lives. Amen.

O Eternal Trinity, my sweet love! You, light, give us light, You, wisdom, give us wisdom; You, supreme strength, strengthen us. Today, eternal God, let the cloud of our self-love be dissolved, so that we may perfectly know and follow Your Truth in truth, with a free and candid heart.
St. Catherine of Siena, prayer XXII

O Immeasurable Love, Sweet Love, Eternal Fire! You are a flame ever burning, high, eternal Trinity! Turn the eye of Your mercy upon Your creatures. I know that mercy is Your attribute, and wherever I turn I find nothing but mercy. Hence do I run and cry out in the presence of Your mercy: have mercy on the world.
St. Catherine of Siena, prayer XIX