Can I pursue a PhD in sociology after completing an MBA in HR?

Yes, you can do PhD in sociology after MBA.

1. MBA is post-graduation. It is requirement for PhD.
2. In PhD you study “organization Behavior” – that maps some of its portion/syllabus with Sociology. Some HR topics are also mapped with sociology like diversity, Gender studies, etc.
3. Particularly Organization theory and Organization Change/Culture – often electives, in HR area are closely linked with Sociology. And you can select those courses and area for PhD.
4. In general one can do PhD after post-graduation.