Montserrat -Safe to Travel as Solo Female Traveler?

It's perfectly safe, why would you expect it to be dangerous?
It's easy to get there by trains and as I recall the train stations in Barcelona even have signs directing you to the right train for Montserrat. The topic has been discussed here several times, so a little seaching should give you the information you need.

I think the only safety question is really about the solo hiking. If you have hiked alone previously, you should know the normal safety precautions. Ample water would be most important and sticking to popular paths. Temps are looking to be high 20's to low 30'sC so warm. Ideally, the earlier in the day you can finish your hike the better.
The web has a number of websites with the hiking trails for the area. There is even a site 'walkapedia'...who knew?
I had hoped to see a national park website. If there is one and if there is a visitor's centre, they will be able to provide insight on the best trails and your safety. I expect the safety issue to be less about 'personal safety from others' and more the fact that you are hiking. August will still see a lot of people there, so let's assume safety in numbers. Perhaps you will be able to tag along with some other hikers.
I would also expand your information search to some of the travel websites with more destination specific forums. A forum for Montserrat specifically will most likely provide more first hand knowledge.

EDIT: look at webarcelona dot com. They have a tour that might suit you. It says minimum 2 persons, but perhaps you can email them and see if there is a booking for that date already.....rather than an online booking.

Hi sharmzzz

Yes is totally safe. You'll see that Montserrat is a very popular escapade for tourists and local families alike and that there are always people around, even on the trails. It's nearly impossible to "get lost" unless you decide to take some of the most extreme trails, and even so, they're very well signaled too. As Maria pointed, safety is perhaps more regarding you getting yourself hurt rather than anything else.

Hikes are quite straight forward as the area is very well signaled.

Leaving: that depends on you... people stay until quite late.

Maria's point about a website: yes there is and it's actually quite good as it contains a wealth of information... but it's only available in Catalan, the local language, so you'll need to use Google Translate, http://muntanyamontserrat.gencat.cat/ca/inici/ For info: "senderisme" = Catalan for "hiking" and you can download the hikes to your mobile phone. Also good to know that, while the website is in Catalan only, you can download many hikes in PDF format where's presented in Catalan, Spanish and English. For example, one of the most popular hikes: http://muntanyamontserrat.gencat.cat/web/.content/temes/el_parc/itineraris/arxius/SantJeroni/MontserratSantJeroni.pdf

Advice?... yes, read carefully this post I made a few months ago: https://community.ricksteves.com/travel-forum/spain/a-visit-to-montserrat-the-holy-mountain-near-barcelona-in-catalonia as I am sure it'll answer many of your questions.

Enjoy!

update Seeing Wray's post I must say I totally agree, it's a matter of gut feeling of course. Yet I'd like to point out that when I mentioned "totally safe" I tried to get in the shoes of a "solo female traveller" -albeit obviously I'm not :)

I understand your qualms about hiking alone on unfamiliar trails or in unfamiliar places. As a solo traveler this is the only item I don't do alone (well, or rent a car). I grew up in the country, but turns out I'm really a city girl. I don't feel safe hiking alone for numerous reasons. If your gut says don't, just don't. However, if you hang around the trailhead, perhaps you'll find a few women or couples who will be happy to have you along? That would be my approach. I'd also suggest you create a post with just the hiking question and request women to answer. I made such a post a few years ago for a path in Sweden, which confirmed my instincts were OK.

I agree with Enric. When we were there at the end of Sept it was very busy. We did a number of loops in that area and were never by ourselves. In August I would expect it to be very crowded.