Tzvi was born in 1910 in Tel Aviv to his father Moshe (born in Jerusalem in 1882) and his mother Hasia née Yankelowitz. His grandfather and namesake, Tzvi Hirsch Cohen, founded in the city walls of Jaffa its first hotel, Hotel Eshel. His father Moshe moved it to Siksik Street in Jaffa, naming it Hotel Moshe Cohen. It became a meeting place for those residents of the settlements who had recently made aliyah and the members of the Old Yishuv in Jerusalem. He dedicated himself to helping those who were making aliyah, saving them from boatmen who would rob them, helping ease their entry into the land without the red ticket the Turks required.
Tzvi was the oldest of six children, and the family was Religious Zionist. He studied in the Alliance school and the Herzliya Gymnasium, as well as for a time in Cairo. At a later age, he spent a decade in the United States studying medicine. He was a true Renaissance man, speaking six languages.
When her returned from America, he opened a garage on Shabazi Street in Tel Aviv, and he earned a reputation as an exemplary professional.
In 1945, Tzvi joined Lehi, under the influence of a cousin who was a Lehi activist. Tzvi was instrumental in operations for confiscating weapons, mainly as a deriver and mechanic. In late 1947 and in 1948, he was in charge of the Lehi garage in Sheikh Munis. In particular, he would take care of the vehicles headed to Jerusalem; he himself made the trips many times, bringing firearms, equipment and food. Devora Kapshuk, his future wife, often joined him. He had known her since she made aliyah in 1936. They met again in the 40s, and in 1945 he recruited her for Lehi. “Adam” was their supervisor.
After some Hagana members informed on them, Tzvi and Devora were arrested. They spent two months in Jaffa Prison.
When Lehi was disbanded, they married. They first lived in Petah Tikva, then in Ramat Gan. Tzvi had a garage on the corner of Petah Tikva Way and Lincoln in Tel Aviv.
He fell ill and died on February 23,1963, at the age of 53. He was buried in Kiryat Shaul.
Tzvi was known for his professional acumen, a pleasant and dear man, always ready to help others, faithful and extremely dedicated to his work in Lehi.