It is well known that paper is not stable in time. There are several causes of paper decay, but acidification is by far the main reason. In general the pH is used to express paper acidity. The determination of the pH of paper, a solid material, is a difficult task. Several methods exist, nine of which were evaluated in this study. All methods are destructive and can cause serious damage to the paper investigated. To limit the damage a micro-extraction method was developed that only requires about 40 [mu]m paper for one pH measurement. A different way to express the acidity of a paper sample is the alkaline reserve, a parameter that is often used when analyzing paper with a pH higher than seven. Its determination is quite time- and product-consuming and labour-intensive. This work tested if the pH can be an indicator for the alkaline reserve. -- SCMRE