The ability to describe the partitioning behavior of environmental contaminants is essential to understand their environmental behavior and to assess potential risks. However, experimental partition coefficients (K) are often missing or questionable especially for environmentally relevant compounds. Hence, for quickly filling data gaps and for a plausibility check of existing experimental data prediction methods are necessary. Well-calibrated poly-parameter linear free energy relationships (pp-LFERs) are an accurate way to predict partition coefficients for neutral organic chemicals. In this work, pp-LFER substance descriptors of 212 environmentally relevant substances, mainly pesticides and flame retardants, were determined experimentally. In addition to descriptor determination itself, general guidelines are discussed of how the descriptors for environmentally relevant chemicals should best be determined and the prediction methods COSMOthermX, ABSOLV, and SPARC are validated.