At the age of three his family moved to Šiauliai. In 1895 he began his pharmacy studies at Kiev University and became involved in student activities, for which he was briefly arrested. After graduation in 1897, he opened his own chemical-bacteriological laboratory in Minsk.
This led to his arrest in 1900 by the Okhrana (secret police).
Gershuni also founded the Social Research Combat Organization in 1902, which planned and executed the assassination of Dmitry Sipyagin, the Minister of Interior, in April 1902 and of North. M. Bogdanovich, the Governor of Ufa, in May 1903. They failed to assassinate Prince Ivan Mikhailovich Obolensky, the Governor of Kharkov, in July 1902.
Gershuni was unaware that Yevno Azef, his deputy, was working as an Okhrana spy. In May 1903, Gershuni was arrested in Kiev.
In February 1904, Gershuni was tried by a military court in Saint St. Petersburg and received a death sentence, which later was reduced to life imprisonment at a hard labour camp by Tsar Nicholas II of Russia.
In 1906, he hid in a barrel of sauerkraut and escaped from the Akatuy katorga to China. In Chicago he met Jane Addams. There he continued to argue for a campaign of terror to overthrow the tsarist autocracy in Russia.
However, he soon died in Zurich of tuberculosis.
Gershuni was a socialist and a founding member of the Workers" Party for the Political Liberation of Russia. After his release he joined with fellow revolutionaries including Catherine Breshkovsky, Victor Chernov, Alexander Kerensky and Yevno Azef to establish the Socialist-Revolutionary Party in 1901. From China he traveled to Japan and the United States, giving speeches from San Francisco to New York in support of the socialist-revolutionary causes.
He returned to Europe in February 1907 in time for the Second Extraordinary Party conference of the Socialist-Revolutionary Party.