Carlton Cole tested Portsmouth's defence but failed to find the net
West Ham halted their losing streak with their first clean sheet of the season and a point, but they could easily have had all three.
Portsmouth's three best first-half chances fell to Jermain Defoe but despite the visitors dominating, keeper Robert Green was rarely tested.
Craig Bellamy's second-half free-kick that hit the bar for West Ham was the best chance for either side.
That chance inspired the hosts to go on the attack but Portsmouth held on.
West Ham entered the game with just one point from their last six matches, and began full of intent, but for all their endeavour, they struggled to trouble Portsmouth goalkeeper David James.
The England number one was one of three former West Ham players in the Pompey line-up and it was the other two, Glen Johnson and Defoe, who combined to produce the game's first two meaningful goal chances.
Both came as a result of Johnson cutting in from the right wing, highlighting his marker Herita Ilunga as a potential chink in the West Ham armour.
In the first instance Johnson slipped the ball into the path of Defoe, who was put off his shot by the advancing Green, and the second came as a result of Johnson trying a shot himself.
Green could only pat the ball down into the path of Defoe but the keeper gathered the ball at the second attempt.
Another Defoe effort was deflected wide of the post by a touch off the inside of Ilunga's leg as the former West Ham striker came closer to scoring against his former side, while the Hammers were reduced to long-range efforts from Jack Collison.
Early in the second half, Green was forced into making two fine saves as Defoe went closer to a seemingly inevitable goal before Bellamy, who had been quiet for most of the game, smashed the crossbar with a free-kick after a foul on Valon Behrami.
This roused the home fans and inspired West Ham to go on the offensive, but the absence of an effective target man up front was glaringly obvious.
With the home side stretched at the back, Defoe in particular, was threatening to snatch a late winner, but neither team were clinical enough to take all three points.
West Ham manager Gianfranco Zola on their first clean sheet of the season:
"It's been a problem for a while, so today was important - we didn't create a lot but a clean sheet is excellent for the players' morale.
"Robert Green was outstanding, I'm pleased for him as we concede a lot of goals and I'm sure it's frustrating for him, but I think today made up for it.
"Today was a tough match - they gave everything, which is a good thing for me."
Portsmouth manager Tony Adams:
"We had enough chances to have won it, but in the current climate of everyone beating everyone else, I thought that West Ham could go up and get what to me would be an unjust winner.
"I'm very proud of the guys, it feels like its a couple of points dropped but we certainly played well enough to get all three.
"Jermain Defoe had some great chances, I told him that on another day he'd get a hat trick but I think he was trying too hard today as it was his old club."
West Ham: Green, Neill, Collins, Upson, Ilunga (Faubert 61), Behrami, Parker (Mullins 75), Collison, Sears (Etherington 46), Cole, Bellamy. Subs Not Used: Lastuvka, Davenport, Bowyer, Di Michele.
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