In this work, synthetic data report the synthesis of SnO2 nanowedges and In2S3 nanoparticles using literature techniques and SnO2–In2S3 heterostructures by approaches as fully described in the paper. The following supporting data are deposited. Powder X-ray diffraction (PXRD) data (20–80° 2θ) using Ni-filtered Cu Kα (λ = 0.15418 nm) radiation (40 kV and 40 mA) and a data step size of 0.033° 2θ. Data are in raw (Excel) format. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) evaluated morphology of nanocomposites. Analysis was on a field emission (FE) TESCAN MIRA 3 SEM (accelerating voltage 30 kV) at low resolution. EDX data were obtained using a Horiba EX-400 and identified Sn, In and S content in the entirety of the corresponding SEM image. Transmission electron microscopy (TEM) analysis was on a FEI Tecnai 20 (accelerating voltage 200 keV, 70 μm objective aperture). Samples were sonicated in EtOH (15 min) then drop-cast onto 400 mesh lacey carbon on copper (Agar Scientific). Low magnification brightfield imaging (scale bars 500 nm) were employed to obtain an idea of nanocomposite size and coating. High-resolution (HR) brightfield imaging (see ESI) was done on In2S3 (scale bar 5 nm). Rietveld analysis used MAUD software with Rietveld whole profile fitting. Correction used a specially processed Si standard. Cagliotti parameters, Gaussianity parameters and asymmetry of the instrument were kept constant during refinements. Peaks were modelled using a pseudo-Voigt function with asymmetry compensating for broadening caused by particle size and strain. The background of diffraction patterns was fitted with a 4° polynomial and peak positions were corrected by refining the zero-shift error. For inductively coupled plasma-optical emission spectroscopy (ICPOES), a Thermo Scientific iCAP 7400 ICP-OES analyser was used. 2–10 mg of sample was mixed with 10x Na2CO3, ground, and transferred to Haldenwanger Al2O3 combustion boats, sputter coated (4 × 10 nm Pt) with a Quorum Technologies Q150T ES Turbo-Pumped Sputter Coater. Glass slides for use as crucible lids were likewise sputter coated. X-ray photoelectron spectroscopy (XPS) is presented in raw (Excel) formats. XPS signals were referenced using the C1s peak at 284.6 eV. Raman data used a Horiba LabRAM HR Evolution microscope with a 532 nm laser, a 600/mm grating, and a 50% ND filter. Each spectrum had an acquisition time of 5 s and 15 accumulations and data can be opened with OriginPro. A Varian Cary-50 UV–Vis spectrophotometer with a Harrick Video-Barrelino diffuse reflectance probe was used for UV-DRS. A cylindrical sample holder (4 × 10 mm) sat under the DRS probe. Again, use OriginPro. Photocatalytic activity was analysed in triplicate by degrading methyl orange under simulated solar irradiation (150 W Xenon lamp AM 1.5 G filter, 1 sun illumination, 100 mW cm-2). 5 mg of catalyst was added to 25 ml of 4.6 x 10–5 M aqueous dye at pH 7. The mixture was stirred in the dark for up to 120 mins. 2.0 ml aliquots were withdrawn and centrifuged. The 464 nm absorption for the dye was used to determine the dye concentration before photocatalysis (on a PerkinElmer Lamda 750 spectrophotometer). The remaining solution was kept on ice and then irradiated. 2 ml aliquots were obtained at 30, 60, 120 mins. and studied by UV-vis spectroscopy. Reference experiments with irradiation using SnO2, In2S3 or Degussa P25 are reported as are reference experiments without catalyst. Photocatalytic data can be viewed in Excel. To show hydroxyl radical photoformation a terephthalic acid (TA) probe was used. Catalyst (5 mg) was dispersed 30 ml TA (5 × 10−4 M), NaOH (2 × 10−3 M). During irradiation, 3.0 ml aliquots were withdrawn, centrifuged, and the fluorescence emission of the supernatant measured (excitation at 315 nm, emission at 425 nm for hydroxylated TA) with an Edinburgh Instruments FLS980 PL spectrometer. Data can be viewed in OriginPro.