Chemical solution deposition of smooth amorphous Al2O3 thin films has been successfully used for planarization of long-length metallic substrates for 2G HTS superconducting wires production. A series of metal-organic precursors based on Al((PrO)-Pr-i)(3), Al(acac)(3), acetic acid, monoethanolamine (MEA) and diethylenetriamine (DETA) was developed. Correlations between the precursor composition and the features of its two-step thermal-induced transformation to amorphous Al2O3 were studied by H-1 NMR, IR spectroscopy and thermal analysis. Utilizing the solutions of {Al((PrO)-Pr-i)(3) + 2.5MEA + 6HAcet} in (PrOH)-Pr-i and {Al(acac)(3) + nDETA} in HAcet (n = 1-3) as precursors for dip-coating, we obtained the long-length Hastelloy C276 substrate covered by uniform amorphous 50-550 nm thick alumina films with surface roughness of about 0.5-1.5 nm. A 20 m long sample of 2G HTS wire with a commercial level of superconducting critical current of up to 300A was prepared based on Hastelloy substrate tape planarized with Al2O3. (C) 2016 Elsevier Ltd. All rights reserved.