Abstract: The invention relates to a process for manufacturing a copolymer foam containing polyamide blocks and polyether blocks, comprising the following steps: mixing the copolymer melt with a blowing agent, said copolymer having a coefficient of thermal diffusivity a and a crystallization temperature Tc; providing a mold of thickness h at a temperature Tm; injecting the mixture of the copolymer and of the blowing agent at a temperature Tp, into the closed mold; foaming the mixture by opening the mold; in which the maintenance time between the injection of the mixture of the copolymer and of the blowing agent into the closed mold and the opening of the mold is within the range extending from (topt?25%) to (topt+25%), topt being expressed in seconds and obtained by equation (I): t opt = - 1 ? 2 ? h 2 a ? ln ? ( ? 4 ? T m - T c T m - T p ) , ( I ) in which a is expressed in m2/s, h is expressed in m and Tm, Tc and Tp are expressed in ° C.