High indoor temperatures in traditional finisher pig buildings may lead to deteriorating production results, increased pen fouling and increased respiration rate and rectal temperature. Floor cooling may improve the thermal conditions for pigs on solid floors during warm periods, and therefore the objective was to investigate whether floor cooling could lower the respiration rate (RR), increase the percentage of pigs located on the solid floor and reduce fouling. In a commercial finisher pig building in Denmark, ten pens were assigned floor cooling and ten pens served as controls. Water was continuously circulated in embedded pipes in the concrete solid floor and the water was cooled when both the return water from the floor and the outdoor air was warmer than set thresholds. These thresholds were adjusted during the investigation and for outdoor temperature it was either 20 or 18°C, and for return water flow 18, 20 or 22°C. The results showed that floor cooling significantly reduced RR and increased the percentage of pigs located on the solid floor at all three return flow temperatures. E.g. at return flow temperature 20°C, in the temperature interval [28;30.1], floor cooling reduced RR from 98 to 50 bpm (P < 0.0001) and increased the percentage of pigs located on the solid floor from 31.8% to 28.2% (P < 0.001). At return flow temperature 18°C and 20°C, the interaction between pen temperature and cooling was significant, hence floor cooling reduced the effect of the pen temperature. RR increased by 6.6 bpm when the pen temperature increased by 1°C in pens without floor cooling and by 1.9bpm in pens with floor cooling. Floor cooling did, however, not affect pen fouling where more than 25% of the solid floor was soiled in 13% of the observations in both cooled and uncooled pens.