•Beneficiation of the iron-oxide Nb-REM ores of the Chuktukon deposit.•Processing of the ores by direct alkaline-acid treatment and nitric acid leaching.•Direct nitric acid leaching of the REE in an autoclave is the most promising route. The Chuktukon niobium-rare earth elements ore deposit is located in Siberia (Russia). Weathered carbonatite crusts are the basis of the ore deposit. The deposit itself is 3.5km in length, about 800 to 1400m in width and up to 200–300m in thickness. The ores are composed of iron-manganese oxides (hydrogoethite, hematite, psilomelane, pyrolusite) and contain 3–7wt.% of rare-earth phosphates (florencite, monazite) and 0.5–1wt.% of niobium oxide (pyrochlore). The ore is completely finely dispersed and consists of oxide particles formed of compact, dense aggregates which makes ore dressing as well as leaching of the rare and radioactive elements very difficult. Several options for processing of these ores have been considered: 1) reduction of the iron oxides to magnetite followed by beneficiation with magnetic separation to produce a rare metal concentrate; 2) processing of the rare earth elements (REE) containing minerals by direct alkaline-acid treatment; 3) processing of the ores using nitric acid leaching in an autoclave.