Context : G29.96 - 0.02 is a high-mass star-forming cloud observed at 70 , 160 , 250 , 350 , and 500 \mu m as part of the Herschel survey of the Galactic Plane ( Hi-GAL ) during the Science Demonstration Phase .

Aims : We wish to conduct a far-infrared study of the sources associated with this star-forming region by estimating their physical properties and evolutionary stage , and investigating the clump mass function , the star formation efficiency and rate in the cloud .

Methods : We have identified the Hi-GAL sources associated with the cloud , searched for possible counterparts at centimeter and infrared wavelengths , fitted their spectral energy distribution and estimated their physical parameters .

Results : A total of 198 sources have been detected in all 5 Hi-GAL bands , 117 of which are associated with 24 \mu m emission and 87 of which are not associated with 24 \mu m emission .
We called the former sources 24 \mu m-bright and the latter ones 24 \mu m-dark .
The [ 70–160 ] color of the 24 \mu m-dark sources is smaller than that of the 24 \mu m-bright ones .
The 24 \mu m-dark sources have lower L _ { bol } and L _ { bol } / M _ { env } than the 24 \mu m-bright ones for similar M _ { env } , which suggests that they are in an earlier evolutionary phase .
The G29-SFR cloud is associated with 10 NVSS sources and with extended centimeter continuum emission well correlated with the 70 \mu m emission .
Most of the NVSS sources appear to be early B or late O-type stars .
The most massive and luminous Hi-GAL sources in the cloud are located close to the G29-UC region , which suggests that there is a privileged area for massive star formation towards the center of the G29-SFR cloud .
Almost all the Hi-GAL sources have masses well above the Jeans mass but only 5 % have masses above the virial mass , which indicates that most of the sources are stable against gravitational collapse .
The sources with M _ { env } > M _ { virial } and that should be undergoing collapse and forming stars are preferentially located at \lesssim 4 ^ { \prime } of the G29-UC region , which is the most luminous source in the cloud .
The overall SFE of the G29-SFR cloud ranges from 0.7 to 5 % , and the SFR ranges from 0.001 to 0.008 M _ { \odot } yr ^ { -1 } , consistent with the values estimated for Galactic H ii regions .
The mass spectrum of the sources with masses above 300 ~ { } M _ { \odot } , well above the completeness limit , can be well-fitted with a power law of slope \alpha = 2.15 \pm 0.30 , consistent with the values obtained for the whole l = 30 \degr , associated with high-mass star formation , and l = 59 \degr , associated with low- to intermediate-mass star formation , Hi-GAL SDP fields .

Conclusions :