With his elder brother Stephen, he deposed Romanos I in December 944, but was overthrown and exiled by the co-emperor Constantine VII (r. 913–959) a few weeks later.

[1] Romanos Lekapenos had risen to power in 919, when he had managed to appoint himself regent over the young Constantine VII and marry his daughter Helena to him.

[7] The historian Symeon Magister records the death of Helena on 14 January 940, and on 2 February of the same year, Constantine married his second wife, Theophano Mamas.

Their father wanted to have his eldest surviving grandson married to Euphrosyne, a daughter of his successful general John Kourkouas.

[10] Predictably, Stephen and Constantine opposed this decision, and prevailed upon their father, who was by this time ill and old, to dismiss Kourkouas in the autumn of 944.

[11][12] Romanos II instead married Bertha, an illegitimate daughter of Hugh of Arles, King of Italy, who changed her name to Eudokia after her marriage.

[13] Their fellow conspirators included Marianos Argyros, the protospatharios Basil Peteinos, Manuel Kourtikes, the strategos Diogenes, and a certain Clado and Philip.

The contemporary Lombard historian Liutprand of Cremona notes that the ambassadors and envoys from Amalfi, Gaeta, Rome, and Provence present in the capital also supported Constantine VII.

[17] On 27 January 945,[14] however, at the urging of their sister, the Augusta Helena, another coup removed the two Lekapenoi from power under the accusation that they attempted to poison Constantine VII, and restored the sole imperial authority to the latter.

The Byzantine chroniclers have their father welcoming them by quoting a passage from the Book of Isaiah, specifically Chapter 1.2:[9] "Hear, O heavens, and give ear, O earth; for Jehovah hath spoken: I have nourished and brought up children, and they have rebelled against me.