Bioliltration is the most commonly used biological gas treatment technology and is extensively used for the treatment of polluted air with gas flow rates of up to 2 x 10(5) m(3)/h. It involves a filter bed of organic matter serving both as carrier for microorganisms and as nutrient supplier. Polluted gas passes through the filter bed and is cleaned by biological activity. Biofiltration is not being developed in Latin America as in the USA, Canada or Europe; the main reason probably being the absence of specific technology and of potential organic carriers locally available. Five different agriculture by-products available in Latin America: peanut shells, rice husk, coconut shells, cane bagasse and maize stubble, were chemically, physically and structurally characterized for their potential use as biofilter carrier. It was found that peanut shells could be used as biofilter carrier and therefore would have potential biological application.