In a process for monitoring the operation of hydrodeoxygenation of a feedstock, comprising the steps of directing the feedstock to contact a material catalytically active in hydrotreatment, monitoring the temperature in multiple locations of said catalytically active material, and providing an indication in a means for process monitoring when the difference between the temperature in a first location of said catalytically active material and the temperature in a second location of said catalytically active material is above a specified threshold value, the difference between the temperature in said first location of the catalytically active material and the temperature in said second location of the catalytically active material is below the specified threshold value during an initial operation time.