A comparison of the acidic and basic extracts of oil sands process water (OSPW) was performed using positive and negative-ion electrospray ionization (ESI) and atmospheric pressure photoionization (APPI), coupled with a 12 T solariX Fourier transform ion cyclotron resonance mass spectrometer (FTICR MS). In general, the acid-neutral extracts showed higher oxygen content within the negative-ion profiles (both APPI and ESI). The hydrocarbon class was readily observed in the base neutral extract. Furthermore, a comparison of O2S (radical ion) and O2S [H] (protonated) classes in positive-ion APPI data showed significant differences in the distribution of double-bond equivalent (DBE) versus carbon number, which are indicative of differences in structures of the two classes. The S-containing species were relatively more abundant in the base-neutral extract, and the radical O2S ions displayed the characteristic profile of thiophenic compounds. ESI profiles for samples extracted at both pH values (2 and 11) investigated were suitable for characterization of the most polar components within the complex OSPW mixture, while APPI was suitable for the ionization of a broader range of heteroatom classes Because profile comparisons are important for environmental forensics, this study highlights the need for careful attention to extraction pH effects on the measured profiles of OSPW components.