<p>The results of experimental studies on the rheological properties of coal–water suspensions with technical carbon additives are presented. Suspensions based on brown coal were prepared by two methods: in a rotary paddle mixer (RPM) and in a homogenizer with cavitation effect (HCE). It has been proven that the amount of technical carbon in the composition of coal–water suspensions may not exceed 2% by mass. It has been experimentally established that preparation in a homogenizer with addition of carbon provides a homogeneous structure and high sedimentation stability — the separation of suspension with 2 mass % of carbon did not exceed 1 mL over 48 h. The cavitation process is accompanied by heating, which additionally reduces kinematic viscosity by 8–26%. Nanodispersed technical carbon acts as an effective dispersing agent. Suspensions prepared in a rotary paddle mixer had inhomogeneities and were subject to significant separation. It has been proven that the combined use of nanodispersed technical carbon and cavitation homogenization makes it possible to obtain stable and homogeneous coal–water suspensions with low viscosity, suitable for long-term storage and use.</p>