We demonstrate synthesis of freestanding water-soluble indium oxide nanocrystals (In2O3 NCs) by ligand exchange to beta-alanine nitric acid (Ala center dot HNO3) and its application for active channel layer in thin film transistors (TFTs), with investigation of the effect of curing temperatures on the TFT properties in terms of thermal behaviour of the ligand molecules at 150, 300, and 350 degrees C. After ligand exchange from long alkyl ligand (myristic acid, MA) to short Ala center dot HNO3, the mobility of NC TFTs cured at 150 degrees C increased by over 1 order of magnitude, from 1.3 x 10(-4) cm(2)V(-1)s(-1) to 4.5 x 10(-3) cm(2)V(-1)s(-1), due to enhanced tunnelling rate (Gamma) between adjective NCs. Higher curing temperatures such as 300 and 350 degrees C, inducing thermal decomposition of the organic ligands, led to further enhancement of the mobility, particularly up to 2.2 cm(2)V(-1)s(-1) for the In2O3 NC-Ala center dot HNO3 TFT cured at 350 degrees C. It is also found that the ligand exchange of In2O3 NC in acidic condition (e.g. HNO3) would be simple and effective to reduce the surface defects by surface etching, which may lead to better device performances. (C) 2015 Elsevier B.V. All rights reserved.