The diploma thesis deals with the assessment of the effect of the age of oak wood on the burning rate for the purposes of determining the causes of fires. We also dealt with the relative weight loss and duration of flame burning as important characteristics when assessing materials from a fire side. The age of the samples tested was 0, 10, 40, 80 and 120 years from the cutting a tree. We performed the experiment at the premises of the laboratory of the Department of Fire Protection of the Technical University in Zvolen. To perform the experiment, we used a standard test method using the influence of a radiant heat source. The test results showed no influence of the oak age on the relative burning rate