His father Petro Havrylovych Hrekov was a lawyer and a large landowner of the Chernigov Governorate and his mother was Maria Hryhorivna Preobrazhenska.

His first assignment was as the commander of the 2nd Serdyuk Division which was only starting to form and at that time consisted of a small officer corps.

At one time the Soviet Prime-Minister Vladimir Lenin was offering 50,000 rubles in silver for the head of colonel Bolbochan.

[citation needed] During the same time Hrekov was appointed the chief of the Kyiv Military District and was partially involved in the formation of the Sich Riflemen Halych-Bukovyna Kurin (Battalion) led by Yevhen Konovalets.

From December 1918 until January 1919 he was assigned to undertake negotiations with French forces occupying Odessa on behalf of the Directorate of Ukraine.

[2] Under Hrekov's command, between 9 June and 5 July the army of the West Ukrainian People's Republic experienced its greatest success during the Chortkiv offensive, when the Poles were thrown back over 200 km (124 mi).

While there, he edited the journal "Ukraina" but adopted a pro-Polish orientation that discredited him in the eyes of much of the Ukrainian émigré community.

Arrested by the Soviet occupation authorities in 1948 he was taken to Lukyanivska Prison in Kyiv, he was exiled to the Ozerlag camp of the Gulag before being released in 1956, whereupon he returned to Vienna.

Oleksander Hrekov married Natalia Ivanivna Kabat in 1905, the daughter of a Hofmeister of the Higher Court, a secret adviser and senator.

Hrekov had two sisters, Anna and Yulia, as well as three brothers: Kostiantyn who became an attorney, Hryhoriy who was a military officer, and Mykola who was an engineer and railway specialist.