This paper is devoted to investigation of chemical and mechanical paper properties after laser cleaning. In recent years, laser technologies have been widely used in the preservation of Cultural Heritage (CH). One of the main fields of laser application in this area is the cleaning of surfaces of CH objects from natural and anthropogenic contaminations. However, cleaning of books and documents on paper basis requires intensive experimental studies. Comparison of paper properties before and after laser cleaning may prove the safety of laser cleaning. One of the most important parameters that characterize paper strength and durability are hydrogen ion concentration (pH) and absorptivity. We will present experimental results on pH value measurements of paper as well as results on paper absorptivity performed on model samples and real historical artefacts such as books and fragments of newspapers. The results of studies indicate on the neutralising effect of laser irradiation which can be used for the conservation of books and documents on paper base.