Viktor Hahn was born on 21 August 1899 in Kosmonosy, in the Central Bohemian Region near Mladá Boleslav, in what is today Czech Republic. His father was a local butcher. After graduating from a commercial school, Viktor moved to Prague, where he worked as a proxy and bank clerk. There he met his future wife, Ana (Aša) Moravskova, who came from a Catholic family in Vienna. He lived at Jakubowska 8.

During the Second World War, on 3 November 1941, he was deported to the Łódź Ghetto (see Deportations of Jews from the Reich and the Protectorate) on the fifth transport from Prague (vide). He was part of a large group from Prague in a collective (vide) at Jakuba 10 (see). Beginning 1 April 1942, he worked at a dry cleaner (vide) located at Drewnowska 77. This is the date of the first entry in his diary (vide). On 2 May 1942, his name appeared on a deportation list for Chełmno (vide), but he managed to avoid being transported out.  As someone with a job, he appealed the decision and was sent to the so-called over-quota, people who were employed but still appeared on a deportation list. He was lucky once again when a quarantine was announced in the collective due to the outbreak of infectious diseases, which meant that those affected were temporarily not transported. At that time, he responded to an appeal  (see Announcements) calling for people to work outside the ghetto, conducted by the Labour Office (vide). This decision saved his life, because on the day of the last transport to Chełmno, Hahn was among 200 people in the Central Prison (vide), ready to be transported to a transit camp in Litzmannstadt, and from there to a labour camp near Poznań (see Labour camps in Greater Poland). Hahn eventually ended up in a camp in Kobylympole, a district in Poznań, where, beginning on 17 May, he worked on the construction of a railway line and unloading wagons with building materials. The last entry in his diary is 28 May 1942.
On 26 January 1944, Hahn was sent to the Sachsenhausen camp in Oranienburg, Germany (prisoner number 75193). He was then transferred to the Mauthausen subcamp in Ebensee, Austria (prisoner number 138430), on 13 April 1945.  He was liberated on 5 May 1945.

After the war, he returned to Prague. There, he married Aša Moravskova and they had a daughter, Sylvia. He died in November 1981.