A method for reducing the hydrogen aging loss of silica optical fibers by irreversible reaction of the peroxide defects with deuterium is described. This method comprises the step of contacting the optical fiber with deuterium by exposure to a gas mixture containing deuterium at a temperature compatible with the fiber without exposing the fiber to any further activation, and subsequently the step of degassing the fiber in a neutral atmosphere. The invention relates further to a process of producing optical fibers with low hydrogen aging loss wherein an optical fiber is treated using the method for reducing the hydrogen aging loss. Finally, the invention relates to optical fibers with low hydrogen aging loss obtainable by this process and telecommunication cables produced using these optical fibers. Using the new method, an activation step using intense light and/or elevated temperature is not necessary to achieve the reaction of peroxide defects in silica with deuterium. The process according to the invention allows reaction at temperatures such as the ambient temperature without any further activation.