The aim of this article is to emphasize the importance and significance of deacidification as an important and basic conservation process in the preservation of written paper collections. This is a process in which buffer substances are introduced by processing the paper collections, which maintain the pH of the paper within optimal limits for storage. At the same time, they eliminate the possibility of oxidation-reduction processes during future long-term storage. Relatively few chemical reagents are known in practice that have the ability to neutralize acids in paper documents. These are sodium, barium, magnesium, some saponins, amines, borates, phosphates, some polymers of alkaline salts of organic acids. The development of deacidification as a conservation process has been followed and it is concluded that it does not develop rapidly, but is accompanied by too much hesitation and caution. Mass deacidification processes are expensive and cannot provide the desired result and lead to the introduction of essentially different methods. Along with the advantages and disadvantages of each method, the quantitative and qualitative condition of the collections, the institutions find it difficult to select the most appropriate one to be applied to their collections. Bookkeeper, PaperSave Swiss and Bückeburg are listed as effective deacidification methods. These three methods are highly valued as applicable to mass deacidification of documents, in terms of potential for innovation, improvement of mechanical strength and existence, pH and alkaline reserve, cost and risk assessment.