Sheets of acidic and alkaline papers were conditioned in 92% relative humidity, put into stack of interleaved alkaline/acidic sheets, wrapped in a plastic bag, put between two boards and pressed. Four different paper samples changed their original pH from 4.4-5.4 to6.2-6.4 after 3-5 days of contact. Original and treated newspaper and writing papers were aged at 103[degree]C up to 32 days and some mechanical properties were tested. Values of folding endurance, tearing resistance, tensile strength and elongation are significantly higher for deacidified writing paper after accelerated ageing compared to original samples. Difference between acidic and deacidified newspaper after accelerated ageing were not significant, although deacidified paper presents slightly higher values for all tested properties. Despite pH after deacidification failing to reach value 7, the method can be considered a first aid measure for archives and libraries with very limited technical and financial resources. -- SCMRE