Extensive passive seismic monitoring was carried out between September 2017 and September 2018 over the Los Humeros geothermal field in Mexico. This experiment, in addition to several geophysical, geological, and geochemical surveys was conducted in the framework of the European H2020 and Mexican CONACyT-SENER project GEMex for a better understanding of the structures and behavior of the local geothermal system currently under exploitation, and for investigating future development areas. 25 broadband stations (22 Trillium C-120s and 3 Trillium C-20 PH) recording at 200 Hz, and 20 short period stations (Mark L-4C-3D) recording at 100 Hz comprised the network which is sub-divided into two sub-networks. An inner and denser (~1.6-2 km inter-station distance) pseudo-rhomboidal array (27 stations) was laid out to cover the producing zone and retrieve local seismicity mainly associated to injection and production operations, and to comply with beamforming of ambient noise and time reverse imaging techniques. An outer and sparser (~5 km minimum spacing) array was placed at around 30 km radius surrounding the inner network, and was mainly dedicated to larger scale imaging techniques, such as seismic ambient noise tomography, and regional earthquakes tomography. The GEMex project is supported by the European Union’s Horizon 2020 programme for Research and Innovation under grant agreement No 727550 and the Mexican Energy Sustainability Fund CONACYT-SENER, project 2015-04-68074. Waveform data are available from the GEOFON data centre, under network code 6G and are embargoed until Jan 2023.