Comet C/2000 WM1 (LINEAR) was observed at ESO when it had its closest approach to the Earth at the beginning of December 2001 (geocentric distance: 0.32 AU). The aim of the observations was the characterization of the solid component of the coma in order to better understand the origin and the correlation between most aspects of this component. The observations consisted of: broadband (R,I) and narrow band imaging and long slit spectroscopy in the visible with the 1.5m Danish telescope equipped with DFOSC as focal plane instrument; broadband (J,H,K), narrow band imaging, and long slit spectroscopy in the near-IR with the NTT telescope equipped with SOFI as focal plane instrument; narrow-band imaging (5.0, 8.9, 10.4, 11.9, 12.4 μm) in the thermal IR with the 3.6m telescope equipped with TIMMI2 as focal plane instrument. Bad weather conditions prevented observations during almost two of the three half nights awarded to the program. Moreover the high proper motion of the comet caused tracking problems with the 1.5D and the 3.6m telescope. In this paper we present preliminary results of the campaign, focusing on the near-IR data. Results of the observations in the visible are described in another paper.