Colloidal nanocrystals (NCs) compete with molecular catalysts in the field of homogenous catalysis, offering an easier recyclability and a number of potentially advantageous functionalities, such as tunable band gaps, plasmonic properties or a magnetic moment. Using high throughput printing technologies, colloidal NCs can be also supported onto substrates to 2 produce cost-effective electronic, optoelectronic, electrocatalytic and sensing devices. For both catalytic and technological application, NCs surface chemistry and supracrystal organization are key parameters determining final performance. Here, we study the influence of the surface ligands and the NC organization on the catalytic properties of In2S3, both in colloidal form and as a supported layer. In colloidal form, NCs stabilized in solution by inorganic ligands show the highest photocatalytic activities, which we associate with their large and more accessible surfaces. On the other hand, when NCs are supported on a substrate, their organization becomes an essential parameter determining performance. For instance, NC-based films produced through a gelation process provided five-fold higher photocurrent densities than those obtained from dense films produced by the direct printing of NCs