The objective of this work was to develop an electric air-cleaning system for animal houses. An a.c.-powered ferroelectric packed-bed plasma reactor was tested to destroy ammonia and odours in the air. The important parameters affecting reactor performance were investigated: gas residence time in the reactor (4 test levels, 0.2-1.3 s), power voltage (6 levels, 0-15 kV), power frequency (2 levels: 60 Hz and 18 kHz), initial ammonia concentration (3 levels: 21, 27 and 55 ppm). Up to 95% destruction efficiencies were obtained under a combination of test conditions. The plasma reactor was effective in destroying odours in the air taken from a swine room.