In order to identify the comprehensive composition of Arabidopsis mitochondrial ribosome proteins, a strategy based on complementary approaches was used. Classical biochemical purification of ribosomes was combined with the immunoprecipitation of mitoribosomes using a specific Arabidopsis mitoribosome protein as a bait and quantitative proteomics. The immuno-purifications (IP) of the mitoribosome were performed on purified mitochondria from rPPR1-HA plant line (flowers as starting material). IPs were performed performed in different conditions (i.e. with 100, 400 or 600 mM KCl at the IP washing step or 800mM all along the IP). For each condition, experiments were performed in triplicates and IP proteins were identified by quantitative nano LC-ESI-MS/MS. Classic biochemical purification of mitochondrial monosomes (i.e. free ribosomes) was also performed. Starting from purified wild-type Arabidopsis mitochondria (cell culture as starting material), ribosomes were separated on high resolution 10-30% continuous sucrose gradients and mitoribosome containing fractions were analyzed by quantitative nano LC-ESI-MS/MS.