This paper presents far-infrared (FIR) photometry at 150 μm and 205 μm of eight low-redshift starburst galaxies obtained with the Infrared Space Observatory (ISO) ISOPHOT. Five of the eight galaxies are detected in both wavebands, and these data, combined with IRAS archival photometry, are used to model the dust emission at λ ≥ 40 μm. The FIR spectral energy distributions (SEDs) are best fitted by a combination of two modified Planck functions, with temperatures T ~ 40–55 K (warm dust) and T ~ 20–23 K (cool dust), and a dust emissivity index ε = 2. The cool dust can be a major contributor to the FIR emission of starburst galaxies, representing up to 60% of the total flux. This component is heated not only by the general interstellar radiation field but also by the starburst itself. The cool dust mass is up to ~150 times larger than the warm dust mass, bringing the gas-to-dust ratios of the starbursts in our sample close to Milky Way values, once rescaled for the appropriate metallicity. The ratio between the total dust FIR emission in the range 1–1000 μm and the IRAS FIR emission in the range 40–120 μm is ~1.75, with small variations from galaxy to galaxy. This ratio is about 40% larger than previously inferred from data at mm wavelengths. Although the galaxies in our sample are generally classified as 'UV-bright', for four of them the UV energy emerging shortward of 0.2 μm is less than 15% of the FIR energy. On average, about 30% of the bolometric flux is coming out in the UV-to-nearIR wavelength range; the rest is emitted in the FIR. Energy balance calculations show that the FIR emission predicted by the dust reddening of the UV-to-nearIR stellar emission is within a factor ~2 of the observed value in individual galaxies and within 20% when averaged over a large sample. If our sample of local starbursts is representative of high-redshift (z ≥ 1), UV-bright, star-forming galaxies, these galaxies' FIR emission will be generally undetected in sub-mm surveys, unless (1) their bolometric luminosity is comparable to or larger than that of ultraluminous FIR galaxies and (2) their FIR SED contains a cool dust component.This paper presents far-infrared (FIR) photometry at 150 μm and 205 μm of eight low-redshift starburst galaxies obtained with the Infrared Space Observatory (ISO) ISOPHOT. Five of the eight galaxies are detected in both wavebands, and these data, combined with IRAS archival photometry, are used to model the dust emission at λ ≥ 40 μm. The FIR spectral energy distributions (SEDs) are best fitted by a combination of two modified Planck functions, with temperatures T ~ 40–55 K (warm dust) and T ~ 20–23 K (cool dust), and a dust emissivity index ε = 2. The cool dust can be a major contributor to the FIR emission of starburst galaxies, representing up to 60% of the total flux. This component is heated not only by the general interstellar radiation field but also by the starburst itself. The cool dust mass is up to ~150 times larger than the warm dust mass, bringing the gas-to-dust ratios of the starbursts in our sample close to Milky Way values, once rescaled for the appropriate metallicity. The ratio between the total dust FIR emission in the range 1–1000 μm and the IRAS FIR emission in the range 40–120 μm is ~1.75, with small variations from galaxy to galaxy. This ratio is about 40% larger than previously inferred from data at mm wavelengths. Although the galaxies in our sample are generally classified as 'UV-bright', for four of them the UV energy emerging shortward of 0.2 μm is less than 15% of the FIR energy. On average, about 30% of the bolometric flux is coming out in the UV-to-nearIR wavelength range; the rest is emitted in the FIR. Energy balance calculations show that the FIR emission predicted by the dust reddening of the UV-to-nearIR stellar emission is within a factor ~2 of the observed value in individual galaxies and within 20% when averaged over a large sample. If our sample of local starbursts is representative of high-redshift (z ≥ 1), UV-bright, star-forming galaxies, these galaxies' FIR emission will be generally undetected in sub-mm surveys, unless (1) their bolometric luminosity is comparable to or larger than that of ultraluminous FIR galaxies and (2) their FIR SED contains a cool dust component.