hE data, obtained at 298.15 K and atmospheric pressure, are presented for the binary systems alkyl formates (propyl and butyl) with n‐alkanes (n‐heptane, n‐octane and n‐nonane) and with 1‐chloroalkanes (1‐chloropentane, 1‐chlorohexane, 1‐chloroheptane and 1‐chlorooctane). The results for hE indicate interactions of alkyl formates which are stronger with aliphatic hydrocarbons than with alkyl chlorides. Experimental results are examined on the basis of the UNIFAC group‐contribution model. In general, the model represents the available experimental hE data with limits of errors smaller than 8%.