The paper commemorates the 30th anniversary of the severe nuclear accident at the Fourth Unit of the Chernobyl Nuclear Power Plant. Results of the investigation of radioactive glassy lava-like materials formed as a result of the accident are presented. Leaching of Pu, Am and Cs in distilled water and sodium carbonate solution at 25 degrees C from matrices of black and brown Chernobyl "lava" is comparable, however, leaching of Cs from black "lava" in seawater at 25 and 90 degrees C is almost 2 times higher than that for brown "lava". Chemical alteration of black and brown "lava" in seawater is much more intensive that in distilled water and sodium carbonate solution. Comparison of leaching behavior of Chernobyl "lava" and aged samples of nuclear glass is not clear so far because of the lack of data. Further study of Chernobyl "lava" as analogues of vitrified high level waste (HLW) and possibly, Fukushima's corium is needed. (C) 2016 Elsevier Ltd.