The reaction between squaric acid with one equivalent of alkyl isocyanides such as t-butyl isocyanide, cyclohexyl isocyanide and n-butyl isocyanide in ethanol at room temperature after 3h afforded the corresponding squaramic acid derivatives. Symmetric 2,4-squaryl diamides were obtained when the reaction of squaric acid was carried out with two equivalents of alkyl isocyanides under the same conditions. Asymmetric 2,4-squaryl diamides were obtained by reaction of squaramic acids with one equivalent of alkyl isocyanides.Keywords: squaric acid, squaramic acid, symmetric and asymmetric squaryl diamides 1676, 1603, 1536, 1484, 1218 cm −1 , 1 H NMR (500 MHz, d6-DMSO): δ = 0.84-1.46 (7H, m, n-butyl), 1.23 (9H, s, t-butyl), 2.75 (2H, t, J = 7.3 Hz), 5.51 and 7.99 (2 H, D 2 O-exchangeable OH and NH) ppm. 13 C NMR (125 MHz, d6-DMSO): δ =