The Langmuir-Blodgett thin films of n-tetraphenyl porphine iron (III) chloride, n-tetraphenyl porphine manganese (III) chloride, n-tetrakis (4-methoxyphenyl) porphine cobalt (II) and n-octaethyl porphine cobalt (II) mixed with arachidic acid were used as sensing elements for optical detection of capsicum (chili) aroma. The sensing sensitivity of aroma was based on changes of optical absorption of the films taken at four wavelengths i.e. 646, 615, 601 and 585 nm. The responses of the films upon aroma exposure were fast and recoverable. The patterns of the absorption changes were able to distinguish three capsicum samples; dried capsicum annum, fresh capsicum annum and capsicum minimum.