The Scriptures clearly claim and reveal the Lord Jesus Christ as the Jehovah of the Old Testament.
The Lord Jesus Christ who is the Word become flesh is the Jehovah of the Old Testament. The OT appearances or manifestations of God is none other than the appearances or manifestations of the second Person of the Trinity, the Lord Jesus Christ Himself. Therefore all Theophanies are actually Christophanies.
We prove this in the following ways.
Genesis 1.1 says, “In the beginning God created the heavens and the earth.”
Ref. Ps.96.5, Isa.42.5, 45.8,12,18 with Col.1.16, Jn.1.3, Eph.3.9, Heb.1.2,10 (Psa.45.6-7, 102,24-27)
Isaiah 6.1-5 The prophet Isaiah saw the LORD sitting upon a throne, high and lifted up, and his train filled the temple. The seraphim cried out, “Holy, holy, holy, is the LORD of hosts; the whole earth is full of his glory.” And Isaiah cries out, “Woe is me! For I am undone, because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips; for mine eyes have seen the King, the LORD of hosts.”
Isaiah 7.14 says, “Therefore the Lord himself shall give you a sign; Behold, the virgin shall conceive, and bear a son, and shall call his name Immanuel.”
Isaiah 8.13 says, “Sanctify the LORD of hosts himself, and let him be your fear, and let him be your dread.”
Ref. 1Pet.3.15 “Sanctify the Lord the Christ in your hearts…”
Isaiah 9.6-7 says, ”For unto us a child is born, unto us a son is given, and the government shall be upon his shoulder; and his name shall be called Wonderful, Counselor, The Mighty God (Gen.49.24, Isa.10.20-21 Jer.32.18), The Everlasting Father, The Prince of Peace. Of the increase of his government and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with justice and with righteousness from henceforth even forever. The zeal of the LORD of hosts will perform this.
Eccl.12.14 ref. 1Cor.4.5
Isaiah 12.2 says, “Behold, God is my salvation; I will trust, and not be afraid; for the LORD, even the LORD, is my strength and my song; he also is become my salvation.”
Ref. 2Tim.2.10, 3.16
Isaiah 26.12 says, “LORD, thou wilt ordain peace for us; for thou also hast wrought all our works in us.”
Ref. Ps.29.11 & Jn.14.27
Isaiah 26.21 says, “For, behold, the LORD cometh out of his place to punish the inhabitants of the earth for their iniquity; the earth also shall disclose her blood, and shall no more cover her slain.”
Ref. Jude verses 14-15 “…Behold, the Lord cometh with ten thousands of his saints, to execute judgment upon all, and to convict all that are ungodly among them of all their ungodly deeps which they have ungodly committed, and of all their hard speeches which ungodly sinners have spoken against him.”
Ref. Rev.19.11-16 says, “And I saw heaven opened and, behold, a white horse; and he that sat upon him was called Faithful and True, (1.5, 3.7,14) and in righteousness he doth judge and make war.  His eyes were like a flame of fire,(1.14, 2.18) and on his head were many crowns; and he had a name written, that no man knew, but he himself.  And he was clothed with a vesture dipped in blood;(Isa.63.1-8) and his name is called The Word of God.(Jn.1.1,14)  And the armies that were in heaven followed him upon while horses, clothed in fine linen, white and clean.  And out of his mouth goeth a sharp sword,(1.16,2.12) that with it he should smite the nations, and he shall rule them with a rod of iron; and he treadeth the winepress of the fierceness and wrath of Almighty God.  And he hath on his vesture and on his thigh a name written, KING OF KINGS, AND LORD OF LORDS.(Rev.17.14; Deu.10.17; Ps.136.1-4; 1Tim.6.15)
Isaiah 33.22 says, “For the LORD is our judge, (Jn.5.27) the LORD is our lawgiver, the LORD is our king (Lk.1.33); he will save us.(Mat.1.21)”
Ref. Mat.27.11 The Lord Jesus claims to be the King of the Jews.(Jn.18.37) & Ac.17.7
Isaiah 40.3 says, “The voice of him that crieth in the wilderness, Prepare ye the way of the LORD, make straight in the desert a highway for our God.”
Ref. Mat.3.3; Mk.1.3; Lk.3.4 The expression “way of the LORD” is translated “the way of the Lord”.
In this connection also see Malachi 3.1 “Behold, I will send my messenger, and he shall prepare the way before me…”
Ref. Mk.1.2 “The words ‘before me’ in Malachi referring to Jehovah, now become ‘before thy face’ and ‘before thee’ – referring to the Lord Jesus Christ.
Isaiah 40.10 says, “Behold, the Lord GOD will come with strong hand, and his arm shall rule for him; behold, his reward is with him, and his work before him.
Ref. (Isa.62.11) Rev.22.12
Isaiah 40.11 says, “He shall feed his flock like a shepherd; he shall gather the lambs with his arm, and carry them in his bosom, and shall gently lead those that are with young.
Ref.Ps.23.1, Zec.13.7, Jn.10.11, He.13.20
Isaiah 40.28 says, “Hast thou not known? Hast thou not heard, that the everlasting God, the LORD, the Creator of the ends of the earth, fainteth not, neither is weary? There is no searching of his understanding.(Rom.11.33; Eph.3.8)
Isaiah 41.4 says, “…I, the LORD, the first, and with the last; I am he.”
44.6 “Thus saith the LORD, the King of Israel, and his redeemer, the LORD of hosts: I am the first, and I am the last, and beside me there is no God.’
Ref. Rev.1.17, 2.8, 22.13 The Lord Jesus Christ is the First and the Last, the Jehovah of the OT.
Isaiah 42.8 says, “I am the LORD: that is my name; and my glory will I not give to another, neither my praise to carved images.
Ref. Isa.48.11, Jn.5.23. Heb.1.6
In Isaiah 43.11 Jehovah declares “I, even I, am the LORD, and beside me there is no savior.”
Isaiah 43.14 says, “Thus saith the LORD, your Redeemer, the Holy One of Israel…”
Isaiah 43.15 says, “I am the LORD, your Holy One, the creator of Israel, your King.
Ref. Acts 3.14
Isaiah 43.21 says, “This people have I formed for myself; they shall show forth my praise.
Ref. 1Pet. 2.9
Isaiah 45.15 says, “Verily, thou are a God who hidest thyself, O God of Israel, the Savior.
Ref. Hos.1.7; Acts 4.12; Titus 2.13, 3.4, 2 Pet.1.1
Isaiah 45.21 says, “…And there is no God else beside me, a just God and a Savior; there is none beside me.
Isaiah 45.22 says, “Look unto me, and be saved, all the ends of the earth; for I am God, and there is none else.
Ref. Acts 4.12
Isaiah 45.23 says, “I have sworn by myself, the word is gone out of my mouth in righteousness, and shall not return, that unto me every knee shall bow, every tongue shall swear.
Ref. Rom.14.10-11, Phi.2.11
Isaiah 45.25 says, “In the LORD shall all the seed of Israel be justified, and shall glory.
Ref. 1 Cor.6.11; Gal.2.16
Isaiah 49.26 says, “…and all flesh shall know that I, the LORD, am thy Savior and thy Redeemer, the Mighty One of Jacob.”(60.16) cp. Ps.132.2,5; Hab.1.12
Revelation 22.6 “…and the Lord God of the holy prophets sent his angle to show unto his servants the things which must shortly be done.”
(Rev.1.1, 22.16 It is Jesus who sent his angel)