This repository contains data used for the testing of HTSinfer, a Python-based tool to infer metadata directly from bulk RNA-sequencing data, generated on Illumina platforms. The repository includes the sample tables containing metadata from the 72 self-generated and publicly shared RNA-Seq samples, the 720 samples collected from the SRA database, and the aggregated tables, describing the results of the inference. For testing purposes, HTSinfer was installed from Bioconda and executed with default settings, except for the --records parameter, which was adjusted in the case of the 720 RNA-Seq samples set. HTSinfer was tested with the --records argument set to different values (10 thousand, 100 thousand, 1 million, 10 million, and 0 – indicating all records) to evaluate performance and runtimes. A supplementary table comparing the functionality of HTSinfer with other available metadata inference tools is also available in the repository.