This article deals with the study of the effect of cross section of the cut layer of material and its influence on the specific cutting resistance. Measurement and evaluation were carried out using two machined materials, according to the designation W.Nr. carbon steel 1.1191, which is a reference material for the steel grade and refractory nickel alloy 2.4856. For the purpose of the experiment, longitudinal turning technology with two interchangeable CNMG 120408 - SM and CNMX 1204A2 - SM cutting inserts was chosen. According to the recommended index insert values, two different types of cutting conditions were chosen for each material so that the cross section of the chip remained the same during machining. For each material, the cutting speed was constant and the feed rate and cutting depth were changed. The main goal of the experimental work was comparison of the specific cutting resistance in dependence on different cross section of the removed layer of material. On the basis of measuring of cutting forces by dynamometer Kistler the resulting cutting force was determined and the size of the specific cutting resistance was calculated.