The data set presented is part of the one used in the doctoral thesis “Sistemas de ayuda a la decisión y optimización en problemas de corte de acero”. The author of this doctoral thesis is Óscar Soto-Sánchez and the advisors are Micael Gallego and Francisco Gortázar. The thesis consists of the following works: Sierra-Paradinas, M., Soto-Sánchez, Ó., Alonso-Ayuso, A., Martín-Campo, F.J., & Gallego, M. (2021), An exact model for a slitting problem in the steel industry, European Journal of Operational Research 295(1), 336-347 (DOI: 10.1016/j.ejor.2021.02.048). Soto-Sánchez, Ó., Sierra-Paradinas, M., Gallego, M., Alonso-Ayuso, A., & Gortázar, F. (2024) A heuristic algorithm to improving the coil slitting process in the steel industry, Journal of Heuristics (accepted for publication). Instance repository: https://zenodo.org/records/13918318 Sierra-Paradinas, M., Soto-Sánchez, Ó., Alonso-Ayuso, A., Martín-Campo, F.J., & Gallego, M. (2024), On solving the 1.5-dimensional cutting stock problem with heterogeneous slitting lines allocation in the steel industry, Computers & Industrial Engineering 191, 110120 (DOI: j.cie.2024.110120). Instance repository: https://zenodo.org/records/10123916 This thesis proposes a heuristic algorithm for a cutting stock problem in the steel industry. This problem occurs in a Spanish company and the proposed algorithm is currently in production after being validated on real company data and compared with an exact mixed integer linear optimization model (MILO). The dataset presented here includes twenty instances used in the thesis (the rest cannot be presented for confidentiality reasons). For each instance, the order and coil characteristics are provided, as well as the compatibility between these two. Finally, for each instance, the solution of the model, the heuristic algorithm, and the warm start algorithm are provided. The content of the zenodo repository consists of a Dataset.zip file and a README.pdf file (this file explains the entire content of the dataset). The Dataset.zip file contains the instances, the solutions and the README.md and README.pdf files. Therefore, it is only necessary to download the Dataset.zip file.