Cellulose acetate/polyaniline (PANi) blends show a selective response to the presence of sodium dodecyl sulfate (SDS). Such detection can be monitored by visible absorption spectroscopy. In this article, we show how this is dependent on the pH and temperature. At pH 2, the redshift of the maximum absorbance wave-lenght of blend films is essentially dependent on hydrochloric acid; however, at pH 3, this effect clearly, decreases, and at pH values between 4 and 6, the alteration of the blend color depends only on SIDS. The selective detection of SDS is faster with a higher percentage of PANi in the blend. At 25 degrees C, the mechanism of sorption is essentially Fickian for Short times, but this changes at higher temperatures, and at temperatures of 40 degrees C and higher, the sorption kinietics show an initial time lag in which no visible response from the blend to SDS is detected. The response rate of blends to SDS detection increases with the temperature. and PANi content. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1947-1953, 2009