Detection and qualification of process-related impurities assume importance in pharmacological drug development programmes. From time to time, preliminary investigations of such compounds might direct us to better drug options. Impurity profiling also tells us about the toxicity impacts due to the possible carry-over of such molecules into drug formulations. This paper depicts the structural and spectral investigation of 5-(4-Methoxyphenyl)-3-methyl-1-oxa-3-azaspiro[5,5]undecane (VEN-CI), an impurity associated with the anti-depressant drug Venlafaxine (VEN). The structural optimization was performed using Density Functional Theory and the computed data was then compared with experimentally derived data accessible in the literature. The chemical reactivity and stability of the title molecule were evaluated by assessing the HOMO-LUMO energies. The bioavailability and toxicity impacts were also investigated computationally to evaluate the medicinal chemistry friendliness.