There are a number of postdoc seminar series in the Chemistry department. These are run by and for postdocs.
Lecture series showcasing research on organometallic and main group chemistry - follow them on twitter @OxfordOMGSS
Solid State Seminar Series
The Solid State Seminar series is aimed at anyone with an interest in solid state materials chemistry, and consists of one talk by a DPhil student or Postdoc from the Department followed by another talk from an invited external speaker. It is a relatively informal Friday afternoon seminar where students and postdocs are encouraged to get involved in the discussion.
Josh Makepeace and Emily Reynolds organise these seminars, feel free to contact them.