Did a google on 'oven brisket' and came up with this. Hope it helps.

Texas Oven Brisket
This is an absolutely wonderful way to cook brisket. The result is tender, succulent and flavorful. And it's practically foolproof. The wonderful aroma will fill your house and make you, and anyone else who comes along, impatient for it to get done.

* 5- to 6-pound fresh beef brisket, well trimmed
* 1 cup barbecue sauce (your favorite)
* 1/4 cup Worcestershire sauce
* 1/4 cup liquid smoke (Colgin's® is best)
* 1 tablespoon garlic powder
* 2 teaspoons celery salt
* 2 teaspoons lemon pepper
* 1 teaspoon salt
* 1 cup chopped onion
* 1/2 cup water

Preheat oven to 275°F.

In a very large Pyrex baking dish, thoroughly mix all ingredients for sauce. Put the brisket in the baking dish, and turn it over once to coat it with the sauce. Seal the dish tightly with heavy-duty aluminum foil.

Bake at 275°F for 5 to 7 hours (about 1 hour and 15 minutes per pound). Remove from oven and allow to stand for 1 hour before slicing. Slice across the grain, and serve with sauce. Makes 8 to 10 servings.

Note: Before you prepare the brisket, remove it from the refrigerator far enough ahead of time to allow it to come to room temperature.

thank you lakeron.

I found some that said 325 and some that said 250. So didn't know which way to go.

Terri, I've never made a bbq'd brisket, but if it's any help I cook my brisket covered at 325-350 for 2.5-3.5 hours until fork tender. I cannot imagine 7 hours! I'd think it would be falling into shreds by then! But then again maybe that's what you're looking for.

I've made a BBQ Brisket like this

Brisket
1 pkg lipton onion soup mix
1 cup BBQ Sauce
Reynolds Roasting Bag

Put brisket in bag, mix up BBQ sauce and Lipton soup mix, pour over brisket, seal bag. Roast in 325 oven for about 3 hrs.

I wouldn't cook it at 250 without previously heating it to a higher temp. The chance for it to stay a long time at an unsafe temp are too great.
And the amount of salt in a packet of onion soup mix is about the same as 2 teaspoons of salt. Would you pour 2 teaspoons of salt over your meat, then add bbq sauce and roast it? My fingers swell when I eat anything that salty.
I put it into a covered roaster, rub with garlic powder, ground mild red chilis or mild chili powder, spread on some tomato paste, about 1/3 of a small can....then pour a bottle of dark beer into the bottom of the roaster, you can add some onion slices to the top too, put on the lid and put it into a 300 oven for about 5 hours...or 325 for 4...or 350 for 3 hours...doesn't matter much...just so it gets hot enough to kill germs....and doesn't cook too fast.
If you like a smoky flavor, add a very little bit of liquid smoke...like 1/4 teaspoon.
I wrap the cooked meat, and pour off the liquid in the roaster and skim the fat, then slice the cooled meat and reheat in the sauce. It stays in neat slices that way.
Linda C

Rather than using a dry rub, I marinate it overnight in a mixture of red wine vinegar, worcestershire sauce, garlic, seasonings, a dash of Liquid Smoke, etc. It's cooked, covered with foil, at 300. How long depends on size -- for a 3-lb. brisket, the suggested time is 4 hours to begin with.

After the initial cooking period, I drain off all but a tablespoon or so of the grease in the pan (leaving just enough for a little flavor), pour about a cup of BBQ sauce over the meat and return to the oven for another hour. For me, this seems to work a lot better than removing the grease after the fact.

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LindaC I've had this dish many times and it's never been too salty.

Terri, I've cooked mine at about the same temperature as Lakeron's, only difference is I don't let mine sit at room temperature. Instead it goes from the fridge (where it's been marinating overnight), directly into a preheated (very low 240-250°F) oven for 1½ hours per pound.

I don't think this has been mentioned, you might want to leave about ¼" fat cap on the top and definitely bake fat side up.

Sol

Well, reading your post was a real "duh" moment for me, Sol. In this part of the world, we usually barbeque pork and leave the beef to the Texans. :) But a friend shared a recipe, so I tried it. Never having seen one cooked, I just assumed the fatty side should be down, and I guess nobody else knew enough to point out the error of my ways. So for 15 years, I've been cooking beef brisket bassackwards -- literally. lol Thanks for setting me straight!

Terri, I agree with Linda C. about cooking at 250. Actually, I think that's the temp recommended by the Beef Council. BUT their instructions also say it should be seared over fairly high heat first, browning well on both sides before putting it in the oven. If you don't sear to begin with, I believe 300 degrees is about as low as you can safely go.

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Thanks Everyone..Well..I didn't rub it lastnight..and everyone will be home for dinner tonight..(suprise) so I'll quick give it a rub..let it sit for a bit at room temp and put it in at 325..and go from there.

compumom - the recipe called for 1hr 15min per pound and that worked out to 7hrs for the size of that person's brisket.

sol - I see you subscribe to the low and slow method for tough meats.

steelmagnolia - LOL 15years! And you never heard that the fat drips DOWN and bastes the meat. When I do a venison shoulder I put strips of bacon on top to provide the fat.

terri - I know its too late but you could use a meat thermometer.

Ron, the directions for my brisket recipe says that you should cook it that long no matter how large it is. I may leave it close to 4 hours, but no longer. Then again, I remove the brisket from the oven, let it cool, then refrigerate until the next day. Remove the fat, slice and return to the accumulated juices to reheat and serve. It's never failed me yet, but I've never cooked meat for real BBQ like pulled pork or bbq'd beef brisket.

Well, I rubbed it, let it set out for a bit, then baked at 325 for a few hours. Pulled it out and checked on it. Popped the heat to 350 for about 40 minutes, then pulled it out of the oven and let it a rest a bit with the BBQ sauce on it before putting back in the oven for 25-35 minutes at 325. It was perfect and tasty. No need to slice..pulled apart and ate...yummmm.....
Thanks everyone for your dialog and help.