<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10.0pt; mso-ansi-language: EN-GB;\" lang=\"EN-GB\">This paper deals with a hot surface as an ignition source of dust layer. In practice the hot surface is very often underestimated. In combination with the lack of cleaning and subsequent deposition of dust there are very favorable conditions for the initiation of a dust layer, its smoldering or flaming combustion. The paper contains description of parameters which influence ignition of dust layer. Detailed factors such as temperature of hot surface, temperature in room or surroundings, contact time and thickness of dust layer are discussed. Practical part describes testing device and the possibility of its use in practice.&nbsp;</span></p>