In the context of stark differences between Ni-and Co-struvite, we also investigated the evolution of the NixCo1-x-struvites of various metal contents. Namely, for comparison against the pure Ni-and Co-endmembers, ex-situ combined SAXS/WAXS measurements were performed on three isothermally heated NixCo1-x-struvite solid solutions with Ni# = 0.8, Ni# = 0.5 and Ni# = 0.2 and fitted with the same model (ESI: Figure , Table ). As indicated by the BET surface measurements, the amount of mesopores decreased with lowering Ni content. Based on SAXS/WAXS it was further evident that also the pore structure itself changed with different Ni# in the material (ESI: Figure , Table ). The Ni-rich composition with Ni# = 0.8 exhibited majorly a micro-to-mesoporous population with minor macropores as in the Ni endmember. In contrast, the intermediate NixCo1-x-mixtures showed a broad pore size distribution with a significant amount of macropores and a lower amount of mesopores. Finally, the Co-rich NixCo1-x-mixture demonstrated no significant mesoporosity (ESI: Figure , Table ) in correlation with the results from other methods. Cobalt-richer compositions of heated NixCo1-x-struvite shift the pore distribution towards larger pore sizes visible in a scattering signal at lower q and in agreement with the BET data (ESI: Figure , Table ).