Data comprise elemental and radionuclide concentrations in freeze-dried Mediterranean plants, seeds and oven dried soil. The samples were collected in June 2014 along a transect located in the Monfragüe National Park which is within the province of Cáceres, western Spain (start: N 33° 49' 47.2'', W 006° 01' 55.4'', end: N 390 49'46.8'', W 0060 02' 05.1'' (geocentric World Geodetic System 1984 (GPS WG 884)). Thirty plant species (Agrostis pourretii; Campanula rapunculus; Taraxacum sp.; Taraxacum officinale; Rumex scutatus; Hypericum perforatum; Schoenoplectus pungens; Erica umbellata; Phillyrea angustifolia; Myrtus communis; Cytisus sp.; Vitis vinifera subsp. Sylvestris; Crataegus monogyna; Daphne gnidium; Quercus ilex; Ruscus aculeatus; Olea europaea subsp. Europaea; Hordeum murinum; Pistacia terebinthus; Acer monspessulanum; Ficus carica; Cistus ladanifer; Eryngium campestre; Carlina vulgaris; Asparagus acutifolius; Viburnum tinus; Tamarix gallica; Jasminum fruticans; Rubia peregrine; Trifolium campestre) and three soil samples were collected and analysed by ICPMS (Inductively Coupled Plasma Mass Spectrometry) or ICPOES (Inductively Coupled Plasma Optical Emission Spectroscopy) to determine their elemental concentrations. Seeds from six of the plant species were also collected and analysed. Plant samples of sufficient mass (n=16) and the three soil samples were also analysed for selected gamma emitting radionuclides (Be-7, Cs-137 and K-40). The work described here was conducted under both the COMET framework (Fission-2012-3.4.1-604794) (http://www.comet-radioecology.org/) and the TREE project (http://tree.ceh.ac.uk/) funded by the Natural Environment Research Council, Environment Agency and Radioactive Waste Management Ltd. It was also supported by the Centre for Ecology & Hydrology which is part of the Natural Environment Research Council of the UK. Full details about this dataset can be found at https://doi.org/10.5285/05d3cbff-fa40-4c42-84e6-54ce6e7bbf5f