Inclusion complexation of p-sulfonatocalix[4]arene (SC4A) and diphenylamine-4-diazonium chloride (DDC) in aqueous solution was investigated in this study. The inclusion of DDC in the cavity of SC4A leads to H-1 NMR chemical shifts of DDC moving towards higher magnetic field. The complexation of SC4A also results in a bathochromic shift and a decrease in optic intensity of the absorption spectrum of DDC. In the presence of SC4A, the thermal stability of DDC in aqueous solution increases significantly while its photosensitivity still remains high.