Spin-coated films of tetra-(tert-butyl) phthalocyanine copper (CuPc(t-Bu)4) complex were obtained and characterized by Uv-vis absorption spectra and atomic force microscopy. A good linear relationship of the absorbance and solution concentration was detected. Low concentration solution could afford smooth, homogeneous and porous macrostructure film surfaces as indicated by atomic force microscopy. The responses of the film to NH3 were investigated at room temperature. In addition, the response and recovery characteristics, selectivity, stability and effect of thickness of the film to NH3 were also studied. The results indicated that the CuPc(t-Bu)4 spin-coated film could be exploited as an NH3 sensor at room temperature.