Mesoporous polyacrylamides (PAMs) with tunable porosities were synthesized in 1-alkyl-3-methylimidazolium tetrafluoroborates ([Cnmim][BF4], n = 4, 6, 8, 10). The as-synthesized PAM was used as a support for Pd nanoparticles and the Pd/PAM composite showed high catalytic activity and selectivity for the hydrogenation of p-chloronitrobenzene reaction to yield p-chloroaniline.