Hi Sarah! I didn't do a full research but the answer is no. There have been women appointed to the ILC, Concepción Escobar Hernández, Marie Gotton Jacobsson for example for the period from 2012 to 2016

Faivre is right, here is the link http://legal.un.org/ilc/ilcmembe.htm

This does not mean, of course, that all is well and that the number of female members is not ridiculously low. If you want to pursue this further, I suggest you read some of what the elderly white males on the Commission are afraid of, namely feminist approaches to international law, for example the work of Christine Chinkin...

Thanks, Faivre and Frank!

Madam Xue Hanqin, now the judge of ICJ,  used to be a member of ILC.  

I believe that Ms. Paula Escarameia (Portugal) was the first woman elected as a member of the International Law Commission.  Sadly, she has passed away.  See the attached link.

http://www.iccnow.org/documents/Note_on_the_Passing_of_Prof._Paula_Escarameia.pdf

Thank you Guimei and Bennet!

Yes indeed Professor Paula Escarameia of Portugal was the first woman to be elected to the ILC. She was a distinguished lawyer and diplomat, with tireless enthusiasm for justice and human rights, and she was a lovely person. I had the pleasure of working with her when we were each representing our governments at the UN in the 1990s. RIP Paula

In my knowledge, no 

Hello Sarah!  I can confirm you that Prof. Dr. Concepción ESCOBAR-HERNÁNDEZ, is the first Spanish jurist woman in the ILC.

Best regards from University of Jaén (Spain)