Method for in situ activation of at least one hydrotreating catalyst, comprising at least: 1) a step of charging at least one hydrotreating catalyst to a hydrotreating reactor; then 2) a step of injecting a liquid feedstock for hydrotreating, comprising a sulfur content of between 0.01% and 20% by weight, at temperatures of from 120°C to 350°C; then 3) a step of sulfiding said hydrotreating catalyst in the presence of a sulfiding agent; and 4) a step of passivating said hydrotreating catalyst in the presence of at least one nitrogen compound having at least two, more preferably at least three and more preferably still at least four of the following features: a) a nitrogen content by weight of from 15 to 35% by weight, preferably of from 20 to 35%, more preferably of from 20 to 30% and more advantageously of from 20 to 25%, relative to the total weight of the nitrogen compound; b) a number of nitrogen atoms of from 2 to 20, preferably of from 2 to 15, more preferably of from 2 to 10, more preferably still of from 2 to 5 per molecule, advantageously two nitrogen atoms per molecule; c) a boiling point of from 140°C to 300°C, preferably of from 140°C to 250°C, more preferably of from 140°C to 200°C, more preferably still of from 140°C to 175°C; and d) said nitrogen compound being in liquid form at room temperature and at atmospheric pressure, with the proviso that feature b) is always present. 1) a step of charging at least one hydrotreating catalyst to a hydrotreating reactor; then 2) a step of injecting a liquid feedstock for hydrotreating, comprising a sulfur content of between 0.01% and 20% by weight, at temperatures of from 120°C to 350°C; then 3) a step of sulfiding said hydrotreating catalyst in the presence of a sulfiding agent; and 4) a step of passivating said hydrotreating catalyst in the presence of at least one nitrogen compound having at least two, more preferably at least three and more preferably still at least four of the following features: a) a nitrogen content by weight of from 15 to 35% by weight, preferably of from 20 to 35%, more preferably of from 20 to 30% and more advantageously of from 20 to 25%, relative to the total weight of the nitrogen compound; b) a number of nitrogen atoms of from 2 to 20, preferably of from 2 to 15, more preferably of from 2 to 10, more preferably still of from 2 to 5 per molecule, advantageously two nitrogen atoms per molecule; c) a boiling point of from 140°C to 300°C, preferably of from 140°C to 250°C, more preferably of from 140°C to 200°C, more preferably still of from 140°C to 175°C; and d) said nitrogen compound being in liquid form at room temperature and at atmospheric pressure, with the proviso that feature b) is always present. a) a nitrogen content by weight of from 15 to 35% by weight, preferably of from 20 to 35%, more preferably of from 20 to 30% and more advantageously of from 20 to 25%, relative to the total weight of the nitrogen compound; b) a number of nitrogen atoms of from 2 to 20, preferably of from 2 to 15, more preferably of from 2 to 10, more preferably still of from 2 to 5 per molecule, advantageously two nitrogen atoms per molecule; c) a boiling point of from 140°C to 300°C, preferably of from 140°C to 250°C, more preferably of from 140°C to 200°C, more preferably still of from 140°C to 175°C; and d) said nitrogen compound being in liquid form at room temperature and at atmospheric pressure, with the proviso that feature b) is always present.