Can anyone shed some light on the interchangeability of these sentences:

  • "... speaking of which"
  • .. "speaking of such"

I used to think that they are always equivalent and therefore interchangeable but I haven't seen the latter in a while so I'm not sure about its usage. I'd appreciate some examples.


An example of the first could be

I received an email about sproggling today, speaking of which, only yesterday sproggling was mentioned in a lecture.

The second usually has a subject, such as this

I have received a lot of emails about sproggling, mungling and stimming. Speaking of such matters would need some research.


Speaking of which is used by a speaker to refer to a topic that has just been mentioned either by the speaker or someone else.

It is obviously spoken language and comes at the beginning of a new sentence, or could conceivably be placed in a sentence in a dialogue.

Speaking of such can be used in phrase such as; Speaking of such matters can be difficult. But the meaning is not the same as the idiomatic phrase: Speaking of which etc.


Speaking of which is relative, like with which in

I have a wok, with which I cook sometimes.

Nowadays you might be more likely to say “that I cook with”, and analogously “that I'm speaking of” (when I say the following).

I've never used speaking of such, but it seems to me more defensible structurally as the beginning of a sentence. It's the same such that occurs in the phrase as such (when that phrase is not a sloppy substitute for therefore):

I am a member of the club and as such [=as a member] I have access to its facilities.

Speaking of which makes syntactic sense (to me) only as a continuation of the preceding sentence, so it shouldn't be used to begin a sentence in formal writing, in my humble opinion.


"Such" is correct and the same, I just always prefer "which".

  • No such is most definitely incorrect. And sounds non-native. It is wrong for this context. – Lambie Feb 26 '18 at 21:10
  • 2
    I wouldn't go so far as to say "such" is "most definitely incorrect". It is certainly unusual, and from a non-native speaker it will be noticeably non-native, but I wouldn't bat an eyelid if I heard it from a native speaker. (British English.) – Patrick Stevens Feb 26 '18 at 21:15
  • Patrick: "Speaking of such, shall we really discuss this any further?" It is not standard, and I don't mean prescriptively standard. I get tired hearing about BrE versus AmE. Half the time that fact is totally irrelevant. "Speaking of such matters can be tricky." – Lambie 8 mins ago – Lambie Feb 26 '18 at 21:32

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