© 2014 ESO. We describe the processing of the 531 billion raw data samples from the High Frequency Instrument (HFI), which we performed to produce six temperature maps from the first 473 days of Planck-HFI survey data. These maps provide an accurate rendition of the sky emission at 100, 143, 217, 353, 545, and 857 GHz with an angular resolution ranging from 9.I 7 to 4.I 6. The detector noise per (effective) beam solid angle is respectively, 10, 6, 12, and 39 μK in the four lowest HFI frequency channels (100-353 GHz) and 13 and 14 kJy sr-1 in the 545 and 857 GHz channels. Relative to the 143 GHz channel, these two high frequency channels are calibrated to within 5% and the 353 GHz channel to the percent level. The 100 and 217 GHz channels, which together with the 143 GHz channel determine the high-multipole part of the CMB power spectrum (50., 2500), are calibrated relative to 143 GHz to better than 0.2%.