After having followed the usual course in the public school of his native town, Loeb studied at the college of Rouffach and at the lycée of Colmar, in which city he at the same time attended classes in Hebrew and Talmud at the preparatory rabbinical school founded by Chief Rabbi Solomon Klein.

In 1862 he was graduated, and received his rabbinical diploma from the Séminaire Israélite de France in Paris, which had replaced (1859) the Metz École Centrale Rabbinique.

His installation sermon, on the duties of the smaller congregations (Les Devoirs des Petites Communautés), is one of the best examples of French pulpit rhetoric.

The chair of Jewish history in the Rabbinical Seminary of Paris having become vacant through the death of Albert Cohn (1877), Loeb was appointed his successor.

Beginning with the first number, he successfully edited the Revue des Études Juives, the organ of that society, and was, moreover, a voluminous and brilliant contributor thereto.